These band structure engineering options can be used to reduce tunneling probabilities and Auger transition rates compared with a small band gap zincblend structure material. In addition, both strain and quantum confinement can be used to split the light-hole band away from the valence band maximum. The effective masses are not directly related to the band gap and can be separately varied. In small band gap superlattices, such as HgTe/CdTe, In(As, Sb)/InSb and InAs/(Ga,In)Sb, the band gap is determined by the superlattice layer thicknesses as well as by the alloy composition (for superlattices containing an alloy). Prior work has demonstrated room temperature heterojunction n-CdS/p-PbSe photodiodes with responsivity of 55 mA/W and D 5 x 10 8 Jones at 4.7 m wavelength 8. They follow directly from the fact that (Hg, Cd)Te has the zincblend crystal structure and a small band gap. These are undesirable characteristics, which must be designed around, of an IR detector material. This combination of effective masses leads to rather easy tunneling and relatively large Auger transition rates. 0.4) for the alloy compositions required for intrinsic long wavelength IR detection. less than 0.01) whereas the heavy-hole effective mass is ordinary size (M sub hh(exp asterisk)/M sub o approx.
As a result, the electron and light-hole effective masses are very small (M sub(exp asterisk)/M sub o approx. Consequently, the electron and light-hole effective masses are essentially inversely proportional to the band gap. The sensitivity of this region is exploited for thermal sensing over a broad range of temperatures (84 ☌-661 ☌). The (Hg, Cd)Te alloy has the zincblend crystal structure. Due to the submicron diameter, the NFC exhibits an anomalous behavior in close proximity to the odd supermode cut-off wavelength, where the high extinction ratio spectral oscillations exhibit very slow oscillations. The parameter is chosen to set the band gap (cut-off wavelength).
There is one parameter, the alloy composition, which can be varied to control the properties of this material. Small band gap superlattices as intrinsic long wavelength infrared detector materials Intrinsic long wavelength (lambda greater than or equal to 10 microns) infrared (IR) detectors are currently made from the alloy (Hg, Cd)Te.