MOCVD of bandgap-engineered HgCdTe p-n-N-P dual-band infrared detector arrays

Abstract

We report the implementation of recent advances in metalorganic chemical vapor deposition (MOCVD) for in situ growth of four-layer HgCdTe mid wave/ long wave (MW/LW) simultaneous dual-band 64 • 64 infrared detector arrays. This independently accessed, simultaneous, double-heterojunction p-n-N-P dualband detector has two back-to-back stacked photodiodes grown on CdZnTe (100) substrates. The LW photodiode is a p-on-n heterojunction grown on top of an MW N-on-P heterojunction photodiode. Secondary ion mass spectrometry depth profiles of these 28 pm thick p-n-N-P dual-band films show four well-defined regions of alloy composition and doping, and agree well with the device design. 64 x 64 arrays of dual-band detectors were fabricated from these films using electron cyclotron resonance dry etching and CdTe passivation, and hybridized to a dual-band readout chip. Two bump inter-connects in each unit cell provide independent electrical access to the back-to-back MW and LW photodiodes, and allow the MW and LW photocurrents to be separate and independent. The dualband infrared focal plane arrays (IRFPAs) spectral response data at 78K are well-behaved and are fully consistent with that observed in individual singleband LW p-on-n and MW N-on-P heterojunction devices of the same design. The hybridized 64 x 64 dual-band FPAs have MW and LW average in-band quantum efficiencies of 79 and 67%, and median D* values of 4.8 z 1011 and 7.1 x 10 l~ cm-~/Hz/W, in the respective spectral bands at 78K. The data demonstrate that MOCVD has progressed significantly toward being a practical and viable vapor phase in situ growth technology for advanced bandgap-engineered HgCdTe detector arrays.

Infrared detectors: an overview

“…Considerable progress has been recently demonstrated in multispectral HgCdTe detectors employing MBE and MOCVD for the growth of variety devices [54][55][56][57][58][59][60][61]. Also QWIP's technology demonstrates considerably progress in fabrication of multicolour FPAs [40,44,[62][63][64][65][66].…”

Comparative Study of HgCdTe Etchants: An Electrical Characterization

“…With proper theoretical designs different types of emitters and detectors have been studied and many of them have been fabricated. [1][2][3][4][5] During the last few years, there has been tremendous research effort devoted to various aspects of surface treatments, which results in evolution of new surface treatments along the years. 6,7 While sophisticated focal plane arrays of sizes as large as 1,024 · 1,024 and more are now well under the manufacturing phase, there remain many unanswered questions about the nature of HgCdTe surface, answers to which would improve the performance, yield and stability of the focal plane arrays.…”

Passivation effect on optical and electrical properties of molecular beam epitaxy-grown HgCdTe/CdTe/Si layers

“…[1][2][3][4][5] In this material, detector performance is limited by the minority carrier lifetime; the longer the lifetime, the better the device performance in terms of detectivity.…”