Typical quantum-well infrared photodetectors (QWIPs) exhibit rather narrow spectral bandwidths of 1–2 μm. For certain applications, such as spectroscopy, sensing of a broad range of infrared photons is necessary. In this letter, we report on the design of two p-type broadband (BB) QWIPs for detection in the 7–14 μm long-wavelength infrared band. Two different QWIP structures were designed: QWIP-A with three wells of different InxGa1−xAs(x = 0.2,0.25,0.3) compositions and QWIP-B with three wells of In0.25Ga0.75As of different thicknesses (4.5, 5.5, and 6.2 nm) and an undoped GaAs barrier (40 nm thick) to form a unit cell, which are then repeated 20 times to create the BB-QWIPs. The spectral response for QWIP-A covers the wavelengths from the 7 to 11 μm range, while QWIP-B has a broader spectral response bandwidth from 7 to 14 μm. A maximum responsivity of 25 mA/W was obtained for QWIP-B at Vb = 1.1 V, λp = 10.2 μm, and T = 40 K with a spectral bandwidth of Δλ/λ = 63%, a cut-on wavelength at 6.2 μm, and a cut-off wavelength around 14 μm. © 1998 American Institute of Physics.