This paper reports an investigation on techniques for determining elastic modulus and intrinsic stress gradient in plasma-enhanced chemical vapor deposition (PECVD) silicon nitride thin films. The elastic property of the silicon nitride thin films was determined using the nanoindentation method on silicon nitride/silicon bilayer systems. A simple empirical formula was developed to deconvolute the film elastic modulus. The intrinsic stress gradient in the films was determined by using micrometric cantilever beams, cross-membrane structures and mechanical simulation. The deflections of the silicon nitride thin film cantilever beams and cross-membranes caused by in-thickness stress gradients were measured using optical interference microscopy. Finite-element beam models were built to compute the deflection induced by the stress gradient. Matching the deflection computed under a given gradient with that measured experimentally on fabricated samples allows the stress gradient of the PECVD silicon nitride thin films introduced from the fabrication process to be evaluated.

Resonant-cavity-enhanced Hg1−xCdxTe photoconductive detectors for midwave infrared wavelengths are investigated for use in multi- and hyper-spectral sensor systems. Resonant-cavity-enhanced performance is modeled, and compared with measured performance of fabricated devices. The responsivity of fabricated devices shows resonant cavity enhancement, with performance limited by surface recombination.

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Surface passivation has been recognized as a crucial step in the fabrication of mercury cadmium telluride photoconductive as well as photovoltaic detectors. The subject has attracted considerable attention in the past and several reviews existed by 1991. The subject matter, however, received added impetus with the development of techniques like MOCVD and MBE and recently there has been considerable work on MCT passivation using in situ grown II-VI semiconductors. In this report, we have tried to give the present status and identify the issues particularly with reference to the recent work on the subject.

Nanoindentation has been used to investigate the elastoplastic behavior of Hg 0.7 Cd 0.3 Te prepared by molecular beam epitaxy. It was found that Hg 0.7 Cd 0.3 Te had a modulus of elasticity of ϳ50 GPa and hardness of ϳ0.66 GPa. The HgCdTe response to nanoindentation was found to be purely elastic for low loads and developed into ϳ10% elastic and ϳ90% plastic response for higher-load indentation exhibiting significant amounts of creep. The onset of plasticity has been observed to be marked by discontinuities or "pop-in" events in the indenter load-penetration curves at sheer stresses of ϳ1.8 GPa, and has been correlated with the homogeneous nucleation and propagation of dislocations.

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Two experimental techniques have been investigated to examine residual stress in low-temperature plasma enhanced chemical vapour deposited (PECVD) SiN x thin films: one that measures the stress-induced substrate curvature, and the other that takes advantage of the stress-induced deformation of freestanding diagnostic microstructures. A general linear dependence of residual stress on SiN x deposition temperature is observed, with the magnitude of stress changing linearly from ∼300 MPa tensile stress to ∼600 MPa compressive stress as the deposition temperature is decreased from 300 to 100 • C. However, the results deviate from the linear dependence by a different degree for both measurement techniques at low deposition temperatures. The stress values obtained via the substrate curvature method deviate from the linear dependence for deposition temperatures below 200 • C, whereas the values obtained via the diagnostic microstructures method deviate from the linear dependence for deposition temperatures below 100 • C. Stress uniformity over the deposition area is also investigated.