MOCVD grown HgCdTe device structure for ambient temperature LWIR detectors

Abstract

The authors report on advanced metalorganic chemical vapor deposition (MOCVD) grown HgCdTe device structure for an ambient temperature long wavelength infrared radiation (LWIR) detector application. MOCVD technology with a wide range of composition and donor/acceptor doping and without post grown annealing seems to be an excellent tool for HgCdTe heterostructure epitaxial growth structure. The N + /G/π /G/P + /G/n + (where G denotes graded interface region) HgCdTe photovoltaic device concept of a specific barrier bandgap architecture integrated with Auger-suppression is a good solution for high operating temperature (HOT) infrared detectors. Selected problems of photodiode designing are indicated. Theoretical modelling using APSYS platform supports design and better understanding of the carrier transport mechanism in the photodiode structures. SIMS profiles allowed comparing projected and obtained structures and revealed diffusion processes in the structures. The negative differential resistance, clearly visible on current-voltage characteristics, evidences for Auger-suppression due to exclusion and extraction phenomena. It is shown that the thickness and arsenic doping of the active region influence the reverse bias dark current minimum and the response time of LWIR HOT HgCdTe photodiodes. Reverse bias highly (up to 50 times) increases responsivity that could reach 6 A/W at 300 K.

MOCVD Grown HgCdTe Heterostructures

“…Figure 16. Modelled and measured characteristics of dark current density versus bias voltage for LWIR N + /G/π/G/P + /G/n + HgCdTe photodiode at room temperature [29].…”

“…The LWIR N + /G/π/G/P + /G/n + HgCdTe photodiode diagram. x is the alloy composition, N A -the acceptor concentration, and N D -the donor concentration[29].Chemical Vapor Deposition -Recent Advances and Applications in Optical, Solar Cells and Solid State Devices…”

“…Current responsivity versus wavelength for LWIR HgCdTe photodiodes measured at room temperature[29].…”

Status of long-wave Auger suppressed HgCdTe detectors operating > 200 K

“…The post−growth thermal an− neal was not needed and not applied. The detailed descrip− tion of the growth procedure was presented by Piotrowski et al and Madejczyk et al [18][19].…”

Utmost response time of long-wave HgCdTe photodetectors operating under zero voltage condition

“…The higher temperature the peak value of the response time moves to higher reverse voltages. At the same time, assuming that detector is immersed, those devices exhibit D * * 10 9 Jones (Madejczyk et al 2013;Pawluczyk et al 2015;Madejczyk et al 2017). …”