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We have demonstrated Si and Be doped InAs1−xSbx-based heterostructures (0.3 ≤ x ≤ 0.9) for LWIR and VLWIR detection grown by molecular beam epitaxy on semi-insulating GaAs (0 0 1) substrates. Wet etching and electroplating were used to fabricate photoconductive and photovoltaic devices optimized for 50% cut-off wavelengths ranging from 8 to 16 µm at room temperature. Photoelectrical properties of the devices were studied. The devices based on minimum bandgap material were optimized for a high-frequency operation in a wide spectral range with response time down to 100 ps. Other devices doping level in the active layer was chosen to reach high room-temperature detectivity. Furthermore, the implementation of monolithic optical immersion has drastically improved the signal to noise ratio allowing uncooled or Peltier-cooled operation.

In this paper we present the recent progress in the growth of (1 0 0) HgCdTe epilayers using metal organic chemical vapour deposition on GaAs epi-ready substrates. Particular progress has been achieved in the reduction of macro-defects known as “hillocks”, revealed on the surface of HgCdTe epilayers with (1 0 0) crystallographic orientation. The large-scale defects can arise from such sources as poor substrate processing, dust and remnants from previous deposition, and non optimal parameters of nucleation and growth process. In our experiment, hillocks density was decreased to Obtained epilayers are suitable for device fabrication. So far, significant improvements has been obtained in photoconductors operated at near-room temperatures. Devices fabricated from (1 0 0) HgCdTe have about one order of magnitude higher voltage responsivity than their (1 1 1) B counterparts.

The authors report on energy gap engineering solutions to improve the high-temperature performance of long-wave infrared (LWIR) HgCdTe photodiodes. Metalorganic chemical vapour deposition (MOCVD) technology with a wide range of composition and donor/acceptor doping and without ex-situ post grown annealing seems to be an excellent tool for HgCdTe heterostructure epitaxial growth. The heterojunction HgCdTe photovoltaic device based on epitaxial graded gap structures integrated with Auger-suppression is a magnificent solution for high operating temperature (HOT) infrared detectors. The thickness, composition and doping of HgCdTe heterostructure were optimized with respect to photoelectrical parameters like dark current, the responsivity and the response time. In this paper we focus on graded interface abruptness in the progressive optimization.