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.
Development of polyamide curable modified epoxy novolac resins with improved adhesion and chemical resistance
Purpose – To prepare modified epoxy resins from resorcinol, cresol and phenol for improved adhesion and chemical resistance. To evaluate the properties of such modified epoxy resins.Design/methodology/approach – Epoxy novolac resins (ENRs) were synthesised by condensing epichlorohydrin with novolacs based on different types of substituted phenols for improving adhesion and chemical resistance. Various compositions were made by incorporating different proportions of polyamide resin. The chemical and adhesive strengths of the conventional epoxy and the modified epoxy resins were characterised.Findings – The modified ENR using substituted phenols showed significant enhancement of chemical and adhesive strengths over the conventional DGEBA resin. The modified ENR had an increased number of glycidyl groups (thus increased functionality) of resin, which was responsible for improved chemical and adhesive strengths over the conventional DGEBA resin.Research limitations/implications – The EPN resins used in the pr...