Dark currents, responsivity, and response time in graded gap HgCdTe structures

J. Piotrowski; W. Gawron; Z. Orman; J. Pawluczyk; K. Klos; D. Stepien; A. Piotrowski

doi:10.1117/12.850331

3 May 2010 Dark currents, responsivity, and response time in graded gap HgCdTe structures

J. Piotrowski, W. Gawron, Z. Orman, J. Pawluczyk, K. Klos, D. Stepien, A. Piotrowski

Proceedings Volume 7660, Infrared Technology and Applications XXXVI; 766031 (2010) https://doi.org/10.1117/12.850331
Event: SPIE Defense, Security, and Sensing, 2010, Orlando, Florida, United States

Abstract

The nominally sharp interfaces in layered HgCdTe heterostructures are affected by interdiffusion for growth at a temperature of above 300 K. Significant composition and doping grading always occur in layered HgCdTe heterostructures grown with MOCVD (360°C), LPE (480°C), and ISOVPE (500°C) epitaxial techniques. MBE (170°C) is the only technique that practically does not introduce significant diffusion grading, but it can be introduced by post growth processing, especially during dopants activation. The purpose of this paper was to explain how the grading affects performance of photodetectors operating at near room temperatures (190-300 K). Influence of the growth related and intentional grading on dark currents and response time was studied with numerical calculations and experiments. Practical infrared devices with controlled grading were grown with programmed MOCVD and characterized. The studies revealed interesting properties of the N⁺pP⁺ devices with graded interfaces. Controlled grading minimizes Auger, Shockley-Read and tunnel currents, increases responsivity and linearity range. The grading is also important for high frequency performance of the devices.

Citation Download Citation

J. Piotrowski, W. Gawron, Z. Orman, J. Pawluczyk, K. Klos, D. Stepien, and A. Piotrowski "Dark currents, responsivity, and response time in graded gap HgCdTe structures", Proc. SPIE 7660, Infrared Technology and Applications XXXVI, 766031 (3 May 2010); https://doi.org/10.1117/12.850331

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