Electrical characteristics of Hg/sub 1-x/Cd/sub x/Te epilayers subjected to ultrasonic influence
The degradation of electrophysical characteristics of Hg1-xCdxTe thin films grown by LPE and MBE as a consequence of the high-frequency and high-intensity elastic deformation effect was investigated It was determined that parameters of Hg1-xCdxTe thin films grown by MBE are stable to ultrasonic influence whereas for Hg1-xCdxTe thin films grown by LPE the mobility decrease and the change of the conductivity type at low magnetic field wae observed The best agreement between experiment and calculation was obtained in the frame of assumption about forming of the thin layer with opposite conductivity. The possible mechanism of Ihe observing effects was analyzed.
MCT heteroepitaxial 4 × 288 FPA
Abstract 4 × 288 heteroepitaxial mercury–cadmium telluride (MCT) linear arrays for long wavelength infrared (LWIR) applications with 28 × 25 micron diodes and charge coupled devices (CCD) silicon readouts were designed, manufactured and tested. MCT heteroepitaxial layers were grown by MBE technology on (0 1 3) GaAs substrates with CdZnTe buffer layers and had cutoff wavelength λco≈11.8±0.15 μm at T=78 K. To decrease the surface influence of carrier recombination processes the compositionally dependent layers with increase of Cd content both toward the surface and HgCdTe/CdZnTe boundary interface were grown. Silicon readouts with CCD multiplexers with input direct injection circuits were designed, manufactured and tested. The testing procedure, to qualify readout integrated circuits on wafer level at T=300 K, was worked out. The silicon readouts for 4 × 288 arrays, with skimming and partitioning functions included were manufactured by n-channel MOS technology with buried or surface channel CCD register. The HgCdTe arrays and Si CCD readouts were hybridized by cold welding indium bumps technology. With skimming mode used for 4 × 288 MCT n–p-junctions, the detectivity for several tested 4 × 288 arrays was within D λ ∗ ≅9×10 10 –1.8×10 11 cm Hz1/2/W for background temperature Tb=295 K.
Long-wavelength HgCdTe photodiodes: n + -on-p versus p-on-n structures
The performance of long‐wavelength n+‐on‐p and p‐on‐n HgCdTe photodiodes is reexamined theoretically. It is assumed that the performance of photodiodes is due to thermal generation governed by the Auger mechanism. The influence of junction position on the R0A product, photoelectrical gain, and noise for both types of HgCdTe photodiodes operated at 77 K, with 0.1 eV base material, is considered. Especially, the R0A product as a function of cutoff wavelength and temperatures is analyzed in detail for both type of structures. For assumed doping concentrations in the base region of homojunctions (Na=5×1015 cm−3 for the n+‐on‐p structure and Nd=5×1014 cm−3 for the p‐on‐n structure), the influence of a p‐type cap layer on the effective R0A product is more serious for p‐on‐n structures in comparison with influence of an n+‐type layer on the R0A product for n+‐on‐p junctions. Therefore, to suppress the deleterious influence of cap layers (especially in the case of p‐on‐n junctions), a wider band‐gap cap layer is ...