Hybrid infrared focal-plane arrays

In this paper, new results are presented in the development of hybrid infrared focal-plane arrays. Attention is focused on hybrid focal-plane arrays using backside-illuminated InAsSb and HgCdTe photovoltaic detectors which are source-coupled into a charge-coupled device (CCD) multiplexer. Background suppression capabilities of the input circuit, charge skimming and partitioning, are experimentally demonstrated. Data on the uniformity and temperature dependence of the input MOSFET threshold voltage are presented. The temperature dependence of the threshold voltage agrees well with theoretically calculated values. Several aspects of the noise problems associated with the hybrid infrared focal-plane arrays are discussed. Noise of a source-coupled input circuit with a feedback amplifier is analyzed and it is shown that although two new noise sources are added, the circuit can operate with less noise than the simple source-coupled input circuit. To further understand focal-plane operation, a noise performance model has been constructed which gives excellent agreement with experimental data. Finally, the performance of hybrid focal-plane arrays is discussed.