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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.

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The passivation of silicon by low temperature processed dielectrics, particularly SiN, has recently received a great deal of attention for applications in photovoltaics technology. Low surface recombination velocity is a key issue for ongoing improvements of a large variety of silicon based microelectronic devices. This review discusses the various deposition techniques and also gives recent results of nitride passivation. Issues such as the impact of deposition parameters, thermal stability, interface traps and surface recombination velocity measurements are described. The benefits achieved by the passivation process on the photovoltaic device performance are also discussed.The potential of silicon oxynitride, a gradient index material, for the fabrication of integrated optical devices has been presented. Advances in the growth of SiON for application to integrated optics have been summarized. Based on optimized SiON technology the review reports on special purpose wave-guiding structures such as microcavity resonators, electrooptic modulators, polarization splitters and second harmonic generation devices. SiON technology offers a silicon-compatible technology, a waveguiding structure with high dielectric-index contrast, a low optical loss <0.15 dB cm −1 , in the 1550 nm telecommunication window and a negligible polarization dependence.

We have examined the influence of bonded hydrogen on the losses in silicon oxynitride (SiON) planar optical waveguides on silicon substrates having a silicon dioxide buffer layer. In the SiON layer grown by plasma enhanced chemical vapour deposition, hydrogen was mainly bonded to silicon as evidenced by strong absorption at 2160 cm −1 . The concentration of bonded hydrogen was reduced from 1.2 × 10 22 cm −3 to 5 × 10 21 cm −3 as the substrate temperature was raised from 100 to 300 • C. The corresponding change in the loss was from 1.5 to 1.2 dB cm −1 at 632.8 nm.

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