Material Growth And Performance Of Antimonide-based Type-? Superlattices Mid-and Long-wavelength Infrared Photodetectors

Antimonide type-? superlattices(T2SLs)infrared detectors are promising third-generation infrared detectors that detect medium(3-5?m)and long(8-14?m)wavelengths for a wide range of military and civil applications.Among them,InAs/GaSb T2SL long-wave infrared detectors have adjustable band gap,large effective mass of electrons,good uniformity,and other characteristics because of their unique structure.In recent years,Ga-free superlattice(InAs/In(As)Sb)have gradually attracted the interest of investigators.Compared with InAs/GaSb,Ga-free superlattice eliminates the intrinsic defects associated with Ga elements by replacing the GaSb layer with In(As)Sb layer,and reduces the non-radiative complex centers to extend the carrier lifetime.In this paper,high quality long-wave InAs/GaSb superlattice and mid-wave InAs/In(As)Sb superlattice were epitaxially fabricated on GaSb substrates using MBE.InAs/GaSb long-wave superlattice infrared detectors were fabricated and their irradiation properties were investigated.The following research results have been obtained:(1)High-quality long-wave InAs/GaSb T2SL with P?MN structure have been grown on GaSb substrates using MBE.The growth rate,V/?I elemental beam ratio,and substrate temperature of the InAs/GaSb T2SL were systematically optimized.Different interface control methods and optimal source furnace shutter sequences were adopted for different functional layers.Finally,the RMS roughness of InAs/GaSb superlattice is only 1.78?in the range of 10×10?m,and the FWHM₁ is only 26 arcsec;the RMS roughness of InAs/GaSb/Al Sb/GaSb superlattice is 2.2?in the range of 10×10?m,and the FWHM₁ is 20.5 arcsec.The above parameters indicate that the material has high crystal quality.(2)The long-wave InAs/GaSb T2SL devices with P?MN structure were fabricated by the standard detector process,and the effect of space electron irradiation on the device performance was investigated.The results show that the device has a 50%cut-off wavelength of 9.53?m and a 100%cut-off wavelength of 10.86?m;the peak quantum efficiency(QE)is 47.69%,and the QE of the response at long-wave 8?m is 26.82%;the peak detection rate(D*)reaches 4.38×1011 cm Hz^1/2/W.For the application of infrared detectors in complex irradiated environments in space,by studying the effects of different irradiation doses of 1MeV electrons on the electrical properties of single devices of different mesa.The results show that the 1 MeV electron irradiation mainly produces displacement effects on the detector and has a significant impact on the surface leakage current.(3)The MBE growth of Ga-free superlattices at medium wavelengths,including InAs/InAs_0.66Sb_0.34 and InAs/In Sb T2SLs,was investigated.For InAs/InAs_1-xSb_x,the effect of the In Sb interface on the InAs/InAs_1-xSb_x content was investigated.When the substrate temperature is Tc,the FWHM₁ and RMS roughness of the material are only39.3 arcsec and 1.72?,respectively.The FTIR absorption spectrum were measured with a 50%cutoff wavelength of 4.28?m at 300 K and a complete cutoff at 5.1?m.To suppress the dark current of the device,Al As Sb bulk material was inserted as a barrier layer and demonstrated high quality XRD spectrum.The PL spectrum at a temperature of 4 K showed a luminescence wavelength of 4.58?m.For the epitaxial growth of InAs/In Sb T2SL,an effective growth method is proposed.Two indium source furnaces were used to grow the InAs layer and In Sb layer with different growth rates.The strain of the InAs/In Sb superlattice is controlled within 50 arcsec to achieve a relatively ideal material quality.