Higher Operating Temperature IR Detectors of the MOCVD Grown HgCdTe Heterostructures
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https://doi.org/10.1007/s11664-020-08369-3 2020 The Author(s)
TOPICAL COLLECTION: U.S. WORKSHOP ON PHYSICS AND CHEMISTRY OF II-VI MATERIALS 2019
Higher Operating Temperature IR Detectors of the MOCVD Grown HgCdTe Heterostructures P. MADEJCZYK ,1,3 W. GAWRON,2 A. KE˛BŁOWSKI,2 K. MLYNARCZYK,2 ´ ,2 P. MARTYNIUK,1 A. ROGALSKI,1 J. RUTKOWSKI,1 D. STE˛PIEN and J. PIOTROWSKI2 1.—Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland. 2.—Vigo System S.A., 129/133 Poznanska Str, 05-850 Ozarow Mazowiecki, Poland. 3.—e-mail: [email protected]
This paper summarizes progress in metal organic chemical vapour deposition (MOCVD) technology achieved in recent years at the Institute of Applied Physics, Military University of Technology and VIGO System S.A. MOCVD with a wide range of composition and donor/acceptor doping and without postgrowth annealing is a very convenient tool for the deposition of HgCdTe epilayers used for uncooled infrared detectors. Particular attention is focused on: surface morphology improvement, doping issues, diffusion processes during growth study, substrate issues, crystallographic orientation selection. In this respect, MOCVD technology improvement influencing IR detector parameters is shown. CdTe buffer layer deposition allows HgCdTe heterostructure growth on GaAs substrates. Theoretical modelling using APSYS platform supports designing and better understanding of the carrier transport mechanism in detector’s structures. Secondary ion mass spectrometry profiles allows to compare projected and obtained structures and revealed diffusion processes of the elements. A wide range of different types of infrared detectors operating at high operating temperature conditions has been constructed: photoresistors, non-equilibrium photodiodes, dual-band photodiodes, barrier and multiple detectors. The methodical research efforts contributed to the time constant reduction are important in many detector applications. Future challenges and prospects are also discussed. Key words: MOCVD, HgCdTe growth, heterostructure, doping, infrared detectors
INTRODUCTION Because infrared (IR) radiation is common in nature and a wide range of IR detector applications in almost all spheres of human activity, there is constant development of science and technology on IR sensing. The progress in IR detector technology has been associated mainly with semiconductor IR detectors, which are included in the group of photon
(Received January 8, 2020; accepted July 29, 2020)
detectors. They are characterized both by high signal-to-noise ratio and fast response.1 The absorbed photon energy caused by incident IR radiation is comparable to thermal energies of atoms in a detector. The statistical nature of thermal generation of charge carriers is a source of noise which is reduced most commonly by cooling often to a temperature of 77 K. Cryogenic cooling was always a serious obstacle to widespread applications of IR detectors and increasing their operating temperature without detectivit
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