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14 Jan 2008

Volume 92, Issue 2, Articles (02xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 022509 (2008); http://dx.doi.org/10.1063/1.2807274 (3 pages)

Sang-Koog Kim, Ki-Suk Lee, Young-Sang Yu, and Youn-Seok Choi
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Single-shot measurement of ultrafast time-varying phase modulation induced by femtosecond laser pulses with arbitrary polarization

Klaus Hartinger and Randy A. Bartels

Appl. Phys. Lett. 92, 021126 (2008); http://dx.doi.org/10.1063/1.2801515 (3 pages) | Cited 8 times

Online Publication Date: 18 January 2008

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We demonstrate a single-shot measurement of the transient phase modulation due to field free molecular alignment at the revival times of a rotational wave packet. The wave packet is excited by an arbitrarily polarized ultrashort laser pulse in CO2 at room temperature. With this technique the time dependence along the eigenpolarization directions of the linear susceptibility tensor, i.e., the time dependence of its principle components, can be directly observed with high sensitivity.
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33.80.-b Photon interactions with molecules

Linear optical protocol for preparation of N-photon Greenberger–Horne–Zeilinger state with conventional photon detectors

Yan Xia, Jie Song, and He-Shan Song

Appl. Phys. Lett. 92, 021127 (2008); http://dx.doi.org/10.1063/1.2836268 (3 pages) | Cited 29 times

Online Publication Date: 18 January 2008

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We propose a linear optical protocol to generate Greenberger–Horne–Zeilinger (GHZ) state of N distant photons with the certain success probability. The proposed setup involves simple linear optical elements, N pairs of the two-photon polarization entangled states, and the conventional photon detectors that only distinguish the vacuum and nonvacuum Fock number states. This makes the protocol more realizable in experiments.
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03.67.Bg Entanglement production and manipulation

Modulation of the two-photon absorption by electric fields in HgCdTe photodiode

H. Y. Cui, Z. F. Li, Z. L. Liu, C. Wang, X. S. Chen, X. N. Hu, Z. H. Ye, and W. Lu

Appl. Phys. Lett. 92, 021128 (2008); http://dx.doi.org/10.1063/1.2835049 (3 pages) | Cited 10 times

Online Publication Date: 18 January 2008

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We demonstrate the tunability of the two-photon absorption (TPA) coefficient by adjusting the electric field in a HgCdTe (MCT) photodiode with cutoff wavelength of 5.2 μm. The TPA coefficient was measured by using a picosecond pulsed laser with wavelength of 7.92 μm. An enhancement of the TPA coefficient occurs in the space charge region of the MCT pn junction, which can be attributed to the Franz–Keldysh effect induced by the built-in electric field. By applying a reverse bias to intensify the built-in field, the TPA coefficient is found to be further enhanced by a factor of 18.9. This electric field dependence of the TPA coefficient has been fairly interpreted by the pn junction model with the Franz–Keldysh effect included.
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85.60.Dw Photodiodes; phototransistors; photoresistors
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Phosphor-conversion white light using InGaN ultraviolet laser diode

Yun Xu, Lianghui Chen, Yuzhang Li, Guofeng Song, Yuping Wang, Weidong Zhuang, and Zhen Long

Appl. Phys. Lett. 92, 021129 (2008); http://dx.doi.org/10.1063/1.2835703 (3 pages) | Cited 12 times

Online Publication Date: 18 January 2008

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We fabricated a phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet (n-UV) light and phosphors that emit in the blue and yellow regions when excited by the n-UV and blue light, respectively.The relationship of the luminous flux and the luminous efficacy of the white light with injection current was discussed. The luminous flux increased linearly with increasing current above the threshold of the laser diode, and at 80 mA injection current, the luminous flux and luminous efficacy were estimated to be 5.7 lm and 13 lm/w, respectively. The shift of the Commission International de I’Eclairage coordinates, color temperature, and color rendering index with current are very slight and negligible, which indicates that the blue and the yellow phosphors have an excellent stability and a highly stable white light can be obtained by this way.
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42.55.Px Semiconductor lasers; laser diodes
78.55.Et II-VI semiconductors
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Resonantly photopumped lasing and its switching behavior in a photonic crystal nanolaser

Kengo Nozaki, Shota Kita, Yoshiki Arita, and Toshihiko Baba

Appl. Phys. Lett. 92, 021501 (2008); http://dx.doi.org/10.1063/1.2832670 (3 pages) | Cited 1 time

Online Publication Date: 14 January 2008

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A GaInAsP photonic crystal nanolaser was operated by resonant optical pumping in which the effective cavity area was selectively excited. The laser mode intensity was markedly enhanced when the pump wavelength was tuned to a higher-order cavity mode, and room-temperature continuous-wave lasing was obtained in the fundamental mode. Furthermore, the switching behavior due to a modal wavelength shift was clearly observed, suggesting the possibility of bistable operation, and so on.
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42.55.Px Semiconductor lasers; laser diodes
42.65.Pc Optical bistability, multistability, and switching, including local field effects

Electron plasma wave propagation in external-electrode fluorescent lamps

Guangsup Cho, Jung-Hyun Kim, Jong-Mun Jeong, Byoung-Hee Hong, Je-Huan Koo, Eun-Ha Choi, John P. Verboncoeur, and Han Sup Uhm

Appl. Phys. Lett. 92, 021502 (2008); http://dx.doi.org/10.1063/1.2832669 (3 pages) | Cited 8 times

Online Publication Date: 15 January 2008

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The optical propagation observed along the positive column of external electrode fluorescent lamps is shown to be an electron plasma wave propagating with the electron thermal speed of (kTe/m)1/2. When the luminance of the lamp is 10 000–20 000 cd/m2, the electron plasma temperature and the plasma density in the positive column are determined to be kTe ∼ 1.26–2.12 eV and no ∼ (1.28–1.69)×1017 m−3, respectively.
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52.40.Db Electromagnetic (nonlaser) radiation interactions with plasma
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.35.-g Waves, oscillations, and instabilities in plasmas and intense beams
52.80.-s Electric discharges

Pinch current limitation effect in plasma focus

S. Lee and S. H. Saw

Appl. Phys. Lett. 92, 021503 (2008); http://dx.doi.org/10.1063/1.2827579 (3 pages) | Cited 20 times

Online Publication Date: 17 January 2008

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The Lee model couples the electrical circuit with plasma focus dynamics, thermodynamics, and radiation. It is used to design and simulate experiments. A beam-target mechanism is incorporated, resulting in realistic neutron yield scaling with pinch current and increasing its versatility for investigating all Mather-type machines. Recent runs indicate a previously unsuspected “pinch current limitation” effect. The pinch current does not increase beyond a certain value however low the static inductance is reduced to. The results indicate that decreasing the present static inductance of the PF1000 machine will neither increase the pinch current nor the neutron yield, contrary to expectations.
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52.58.Lq Z-pinches, plasma focus, and other pinch devices
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Photoluminescence from a single InGaAs epitaxial quantum rod

G. Sęk, P. Podemski, J. Misiewicz, L. H. Li, A. Fiore, and G. Patriarche

Appl. Phys. Lett. 92, 021901 (2008); http://dx.doi.org/10.1063/1.2832635 (3 pages) | Cited 6 times

Online Publication Date: 14 January 2008

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Microphotoluminescence (μ-PL) experiment has been performed on a structure with InGaAs/GaAs epitaxial quantum rods (quantum dots with the aspect ratio as high as 4.1) grown by depositing short-period InAs/GaAs superlattice by molecular beam epitaxy on GaAs substrate. The exciton and biexciton emission from a single quantum rod has been detected via the excitation power dependence of the μ-PL spectra. The origin of the single rod lines has been confirmed by a rate equation model. For a number of quantum rods within the investigated ensemble, the biexciton binding energy has been determined to be in the range of 1.0–2.2 meV.
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71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors
78.67.Hc Quantum dots
68.65.Hb Quantum dots (patterned in quantum wells)
73.21.Cd Superlattices
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Modeling boron diffusion gettering of iron in silicon solar cells

A. Haarahiltunen, H. Talvitie, H. Savin, M. Yli-Koski, M. I. Asghar, and J. Sinkkonen

Appl. Phys. Lett. 92, 021902 (2008); http://dx.doi.org/10.1063/1.2833698 (3 pages) | Cited 8 times

Online Publication Date: 14 January 2008

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In this paper, a model is presented for boron diffusion gettering of iron in silicon during thermal processing. In the model, both the segregation of iron due to high boron doping concentration and heterogeneous precipitation of iron to the surface of the wafer are taken into account. It is shown, by comparing simulated results with experimental ones, that this model can be used to estimate boron diffusion gettering efficiency of iron under a variety of processing conditions. Finally, the application of the model to phosphorus diffusion gettering is discussed.
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84.60.Jt Photoelectric conversion
61.72.Yx Interaction between different crystal defects; gettering effect

Resonant x-ray scattering from self-assembled InP/GaAs(001) islands: Understanding the chemical structure of quaternary quantum dots

L. N. Coelho, R. Magalhães-Paniago, A. Malachias, J. G. Zelcovit, and M. A. Cotta

Appl. Phys. Lett. 92, 021903 (2008); http://dx.doi.org/10.1063/1.2820756 (3 pages) | Cited 5 times

Online Publication Date: 14 January 2008

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Lattice parameter profiles and the chemical structure of InP self-assembled islands grown on GaAs(001) were determined with x-ray resonant scattering. By accessing four different photon energies, near x-ray absorption edges of two of the atomic species present on the samples, composition maps of all four atomic constituents of these islands were obtained. This experiment was performed for samples grown at two different temperatures and the effect of temperature was associated to Ga-interdiffusion and strain relief in the dots.
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78.70.Ck X-ray scattering
81.16.Dn Self-assembly
81.07.Ta Quantum dots
78.70.Dm X-ray absorption spectra
68.35.Dv Composition, segregation; defects and impurities

Near-zero IR transmission in the metal-insulator transition of VO2 thin films

R. Balu and P. V. Ashrit

Appl. Phys. Lett. 92, 021904 (2008); http://dx.doi.org/10.1063/1.2834367 (3 pages) | Cited 22 times

Online Publication Date: 15 January 2008

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Vanadium dioxide films have been prepared with different thicknesses using radio-frequency magnetron sputtering technique followed by postdeposition annealing in oxygen ambient. Films with a thickness of 300 nm show a switching efficiency of ∼ 74% and most importantly with a near-zero infrared transmission in the switched state. As the film thickness decreases, the inherent transmission in the switched state increases along with reduced switching efficiencies.
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68.55.jm Texture
81.15.Cd Deposition by sputtering
81.40.Gh Other heat and thermomechanical treatments
71.30.+h Metal-insulator transitions and other electronic transitions
78.66.-w Optical properties of specific thin films

Modified Timoshenko formula for bending of ultrathin strained bilayer films

Ji Zang and Feng Liu

Appl. Phys. Lett. 92, 021905 (2008); http://dx.doi.org/10.1063/1.2828043 (3 pages) | Cited 13 times

Online Publication Date: 15 January 2008

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Mechanical bending of nanoscale thin films can be quite different from that of macroscopic thick films. However, current understanding of mechanical bending of nanoscale thin strained bilayer films is often limited within the Timoshenko model [ Timoshenko, J. Opt. Soc. Am. 11, 233 (1925) ], which was originally derived for macroscopic thick films. Here, we derive a modified Timoshenko formula by including the prominent effect of surface stress played in the nanofilms, which gives a much better agreement with the experiments than the classical formula.
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68.60.Bs Mechanical and acoustical properties
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.40.Lm Deformation, plasticity, and creep

Microstructure and recording mechanism of Bi–Fe–(N) layer for high-density write-once optical disk

Hung-Chuan Mai, Tsung-Eong Hsieh, Shiang-Yao Jeng, Chong-Ming Chen, and Jen-Long Wang

Appl. Phys. Lett. 92, 021906 (2008); http://dx.doi.org/10.1063/1.2828335 (3 pages) | Cited 7 times

Online Publication Date: 17 January 2008

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Bi–Fe–(N) thin film as the recording layer of high density digital versatile disk recordable optical disk was developed. For the disk sample with optimized layer structure, maximum partial response signal to noise ratio of 21.1 and minimum simulated bit error rate of 5×10−7 were achieved at the write power = 5.7 mW. Transmission electron microscopy characterization illustrated that the separation of Bi and Fe elements to form the coarse granular structure in the mark regime during laser irradiation comprised of the recording mechanism.
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42.79.Vb Optical storage systems, optical disks

Thermodynamic analysis of hydrogen sorption reactions in Li–Mg–N–H systems

C. Moysés Araújo, Ralph H. Scheicher, and Rajeev Ahuja

Appl. Phys. Lett. 92, 021907 (2008); http://dx.doi.org/10.1063/1.2830703 (3 pages) | Cited 6 times

Online Publication Date: 17 January 2008

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We report a comprehensive first-principles study of the thermodynamics of the hydrogen release reaction from xLiH–yMg(NH2)2 mixtures involving the composition ratios (x = 2, y = 1), (x = 8, y = 3), and (x = 12, y = 3), with special emphasis on the effect of the different intermediate steps. For all three mixing ratios of LiH/Mg(NH2)2 we find that the hydrogen release is initiated by the same reaction with an enthalpy of 46.1 kJ/mol of H2 in excellent agreement with recent experimental results. Additionally, we also investigated the substitution of LiH by MgH2 as reaction partner of Mg(NH2)2 in the fully hydrogenated state.
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68.43.Bc Ab initio calculations of adsorbate structure and reactions
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.60.Cx Enthalpies of combustion, reaction, and formation
84.60.-h Direct energy conversion and storage

Kinetic arrest of martensitic transformation in the NiCoMnIn metamagnetic shape memory alloy

Wataru Ito, Kouhei Ito, Rie Y. Umetsu, Ryosuke Kainuma, Keiichi Koyama, Kazuo Watanabe, Asaya Fujita, Katsunari Oikawa, Kiyohito Ishida, and Takeshi Kanomata

Appl. Phys. Lett. 92, 021908 (2008); http://dx.doi.org/10.1063/1.2833699 (3 pages) | Cited 55 times

Online Publication Date: 17 January 2008

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Magnetic and electrical resistivity changes due to a martensitic transformation in large magnetic fields were investigated in a NiCoMnIn alloy. The transformation is interrupted at about 150 K during field cooling and does not proceed with further cooling. The obtained two-phase condition is frozen at low temperatures and zero field heating releases this condition, inducing a “forward” transformation. These unusual phenomena can be explained by an abnormal behavior in the transformation entropy change and an extremely low mobility of the phase interfaces detected at low temperatures.
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64.70.kd Metals and alloys
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
81.30.Kf Martensitic transformations
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
65.40.gd Entropy

Kinetics of mesa overlayer growth: Climbing of adatoms onto the mesa top

Yong Han, Feng Liu, Shao-Chun Li, Jin-Feng Jia, Qi-Kun Xue, and Byeong-Joo Lee

Appl. Phys. Lett. 92, 021909 (2008); http://dx.doi.org/10.1063/1.2827200 (3 pages) | Cited 4 times

Online Publication Date: 17 January 2008

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We have calculated the energy barriers for an adatom climbing up onto a Pb mesa top either over a facet-facet edge or through a facet-step joint, using a modified embedded atom method. We found that the second process is not only thermodynamically more favorable than the first one but also much faster with a diminishing barrier. Our results provide a plausible explanation for the experimentally observed intriguing growth behavior of a Pb mesa. The underlying mechanisms can be generally applicable to other systems.
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68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation
68.35.Md Surface thermodynamics, surface energies

Mechanisms of amorphous-phase-dependent grain growth in two-phase nanocomposite films: A Monte Carlo analysis

X. J. Hu, Z. J. Liu, and Y. G. Shen

Appl. Phys. Lett. 92, 021910 (2008); http://dx.doi.org/10.1063/1.2834850 (3 pages) | Cited 2 times

Online Publication Date: 18 January 2008

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Monte Carlo calculations of the grain growth in two-phase nanocomposite films with microstructures comprising of nanocrystalline (n) and amorphous (a) phases are presented based on a modified Q-state Potts model. The mechanisms of amorphous-phase-volume-fraction-(Va)-dependent grain growth are observed by analyzing the microstructure evolution. The results show that with Va values increasing to a critical value of 23%, the grain growth transforms from a n-/n-grain boundary (GB)-curvature-driven growth to the a-/n-GB-curvature-driven growth. The driving force for the transition is caused by the energy difference exerted on n/n or a/n boundaries. With further increasing Va, nanograins are completely surrounded by amorphous matrices and the diffusion-controlled growth mode driven by the difference between a-/n-interfacial energies and n-/n-boundary energies has been found. The homogeneity of the grain growth in the nanocomposite films with different Va values is also discussed.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.J- Morphology of films
61.46.-w Structure of nanoscale materials
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Bandgap and effective mass of epitaxial cadmium oxide

P. H. Jefferson, S. A. Hatfield, T. D. Veal, P. D. C. King, C. F. McConville, J. Zúñiga–Pérez, and V. Muñoz–Sanjosé

Appl. Phys. Lett. 92, 022101 (2008); http://dx.doi.org/10.1063/1.2833269 (3 pages) | Cited 33 times

Online Publication Date: 14 January 2008

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The bandgap and band-edge effective mass of single crystal cadmium oxide, epitaxially grown by metal-organic vapor-phase epitaxy, are determined from infrared reflectivity, ultraviolet/visible absorption, and Hall effect measurements. Analysis and simulation of the optical data, including effects of band nonparabolicity, Moss-Burstein band filling and bandgap renormalization, reveal room temperature bandgap and band-edge effective mass values of 2.16±0.02 eV and 0.21±0.01m0 respectively.
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71.20.Nr Semiconductor compounds
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
78.66.Li Other semiconductors
73.61.Le Other inorganic semiconductors
78.30.Hv Other nonmetallic inorganics
78.40.Fy Semiconductors

Spin-orbit splitting of a hydrogenic donor impurity in GaAs/GaAlAs quantum wells

Shu-Shen Li and Jian-Bai Xia

Appl. Phys. Lett. 92, 022102 (2008); http://dx.doi.org/10.1063/1.2833692 (3 pages) | Cited 20 times

Online Publication Date: 14 January 2008

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The electronic states of a hydrogenic donor impurity in GaAs/GaAlAs quantum wells are investigated theoretically in the framework of effective-mass envelope function theory, including the effect of Rashba spin-orbit coupling. The splits of electron energy levels are calculated. The results show that (1) the split energy of the excited state is larger than that of the ground state; (2) the split energy peak appears as the GaAs well width increases from zero; and (3) the maximum split energy reaches about 1.6 meV. Our results are useful for the application of Rashba spin-orbit coupling to photoelectric devices.
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73.21.Fg Quantum wells
73.20.At Surface states, band structure, electron density of states
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
71.55.Eq III-V semiconductors
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor

Electron transport of nanotube-based gas sensors: An ab initio study

Arta Sadrzadeh, Amir A. Farajian, and Boris I. Yakobson

Appl. Phys. Lett. 92, 022103 (2008); http://dx.doi.org/10.1063/1.2829609 (3 pages) | Cited 5 times

Online Publication Date: 14 January 2008

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The effect of physisorption of NO2 gas molecules on quantum transport properties of semiconducting carbon nanotubes is studied using ab initio calculations and Green function formalism. The results show that the conductance change is mainly due to the electric dipole moment of NO2. It is also shown that upon exposure of nanotube to different concentrations of gas, the common feature is the shift in conductance toward lower energies. This suggests that physisorption of NO2 will result in a decrease (increase) in conductance of p-type (n-type) nanotubes with Fermi energies close to the edge of valence and conduction band.
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07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
82.80.Fk Electrochemical methods

Interface studies of ZnO nanowire transistors using low-frequency noise and temperature-dependent I-V measurements

Sanghyun Ju, Sunkook Kim, Saeed Mohammadi, David B. Janes, Young-Geun Ha, Antonio Facchetti, and Tobin J. Marks

Appl. Phys. Lett. 92, 022104 (2008); http://dx.doi.org/10.1063/1.2830005 (3 pages) | Cited 12 times

Online Publication Date: 14 January 2008

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Single ZnO nanowire (NW) transistors fabricated with self-assembled nanodielectric (SAND) and SiO2 gate insulators were characterized by low-frequency noise and variable temperature current-voltage (I-V) measurements. According to the gate dependence of the noise amplitude, the extracted Hooge’s constants (αH) are ∼ 3.3×10−2 for SAND-based devices and ∼ 3.5×10−1 for SiO2-based devices. Temperature-dependent I-V studies show that the hysteresis of the transfer curves and the threshold voltage shifts of SAND-based devices are significantly smaller than those of SiO2-based devices. These results demonstrate the improved SAND/ZnO NW interface quality (lower interface-trap states and defects) in comparison to those fabricated with SiO2.
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85.35.-p Nanoelectronic devices
85.30.-z Semiconductor devices

Piezoelectric nanogenerator using CdS nanowires

Yi-Feng Lin, Jinhui Song, Yong Ding, Shih-Yuan Lu, and Zhong Lin Wang

Appl. Phys. Lett. 92, 022105 (2008); http://dx.doi.org/10.1063/1.2831901 (3 pages) | Cited 49 times

Online Publication Date: 14 January 2008

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Vertically grown cadmium sulfide (CdS) nanowire (NW) arrays were prepared using two different processes: hydrothermal and physical vapor deposition (PVD). The NWs obtained from the hydrothermal process were composed of alternating hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases with growth direction along WZ ⟨0001⟩ and ZB [111]. The NWs produced by PVD process are single crystalline WZ phase with growth direction along ⟨0001⟩. These vertically grown CdS NW arrays have been used to converting mechanical energy into electricity following a developed procedure [ Z. L. Wang and J. Song Science 312, 242 (2006) ]. The basic principle of the CdS NW nanogenerator relies on the coupled piezoelectric and semiconducting properties of CdS, and the data fully support the mechanism previously proposed for ZnO NW nanogenerators and nanopiezotronics.
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85.50.-n Dielectric, ferroelectric, and piezoelectric devices
85.35.-p Nanoelectronic devices

Ohmic contact formation on n-type Ge

R. R. Lieten, S. Degroote, M. Kuijk, and G. Borghs

Appl. Phys. Lett. 92, 022106 (2008); http://dx.doi.org/10.1063/1.2831918 (3 pages) | Cited 34 times

Online Publication Date: 14 January 2008

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Severe Fermi level pinning at the interface between n-Ge and a metal leads to the formation of a Schottky barrier, almost independent on the metal work function. Therefore, it seems impossible to form metal Ohmic contacts on moderately, n-type doped Ge layers. For p-type Ge, the Fermi level pinning works opposite: all metal contacts show Ohmic behavior. This fixed behavior can be altered by the introduction of a thin Ge3N4 layer. Ge3N4 seems effective in reducing Fermi level pinning and, therefore, allows the formation of Ohmic contacts on n-type Ge and a rectifying contact on p-type Ge.
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73.40.Ns Metal-nonmetal contacts
73.40.Ei Rectification
73.30.+y Surface double layers, Schottky barriers, and work functions
73.20.At Surface states, band structure, electron density of states

Violet luminescence in phosphorus-doped ZnO epitaxial films

A. Allenic, X. Q. Pan, Y. Che, Z. D. Hu, and B. Liu

Appl. Phys. Lett. 92, 022107 (2008); http://dx.doi.org/10.1063/1.2834696 (3 pages) | Cited 16 times

Online Publication Date: 15 January 2008

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A violet luminescence band at 3.1099 eV was observed at 12.5 K in phosphorus-doped ZnO epitaxial films deposited by O2 plasma-assisted pulsed laser ablation. The band results from a transition between a shallow donor and a deep acceptor induced by phosphorus doping. The activation energy of the acceptor varies with the phosphorus concentration [P] and is 0.34 eV when [P] is 1.7×1019 cm−3. Under oxygen-rich conditions, the dominant acceptor in P2O5-doped ZnO may be the zinc vacancy, in agreement with recent first-principles calculations.
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78.66.Hf II-VI semiconductors
71.55.Gs II-VI semiconductors
78.55.Et II-VI semiconductors
61.72.uj III-V and II-VI semiconductors

Characterization of AlN metal-semiconductor-metal diodes in the spectral range of 44–360 nm: Photoemission assessments

A. BenMoussa, J. F. Hochedez, R. Dahal, J. Li, J. Y. Lin, H. X. Jiang, A. Soltani, J.-C. De Jaeger, U. Kroth, and M. Richter

Appl. Phys. Lett. 92, 022108 (2008); http://dx.doi.org/10.1063/1.2834701 (3 pages) | Cited 11 times

Online Publication Date: 15 January 2008

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The absolute responsivity of a metal-semiconductor-metal (MSM) photodiode based on high quality AlN material has been tested from the vacuum ultraviolet (vuv) to the near UV wavelength range (44–360 nm). The metal finger Schottky contacts have been processed to 2 μm in width with spacing between the contacts of 4 μm. In the vuv wavelength region, the measurement methodology is described in order to distinguish the contribution of the photoemission current from the internal diode signal. In the wavelength range of interest, AlN MSM is sensitive and stable under brief vuv irradiation. The MSM shows a 200/360 nm rejection ratio of more than four orders of magnitude and demonstrates the advantages of wide band gap material based detectors in terms of high rejection ratio and high output signal for vuv solar observation missions.
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85.60.Dw Photodiodes; phototransistors; photoresistors
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