MOCVD Grown HgCdTe Heterostructures for Medium Wave Infrared Detectors

Abstract

This paper presents the current status of medium-wave infrared (MWIR) detectors at the Military University of Technology’s Institute of Applied Physics and VIGO System S.A. The metal–organic chemical vapor deposition (MOCVD) technique is a very convenient tool for the deposition of HgCdTe epilayers, with a wide range of compositions, used for uncooled infrared detectors. Good compositional and thickness uniformity was achieved on epilayers grown on 2-in-diameter, low-cost (100) GaAs wafers. Most growth was performed on substrates, which were misoriented from (100) by between 2° and 4° in order to minimize growth defects. The large lattice mismatch between GaAs and HgCdTe required the usage of a CdTe buffer layer. The CdTe (111) B buffer layer growth was enforced by suitable nucleation procedure, based on (100) GaAs substrate annealing in a Te-rich atmosphere prior to the buffer deposition. Secondary-ion mass spectrometry (SIMS) showed that ethyl iodide (EI) and tris(dimethylamino)arsenic (TDMAAs) were stable donor and acceptor dopants, respectively. Fully doped (111) HgCdTe heterostructures were grown in order to investigate the devices’ performance in the 3–5 µm infrared band. The uniqueness of the presented technology manifests in a lack of the necessity of time-consuming and troublesome ex situ annealing.

Defect Analysis in a Long-Wave Infrared HgCdTe Auger-Suppressed Photodiode

“…The HgCdTe was grown at 350 • C and a mercury source was kept at a temperature of 160-220 • C. In situ annealing was carried out under mercury-rich conditions to reduce the residual mercury vacancy concentration and to increase the uniformity of the HgCdTe heterostructures, which allowed ex situ annealing to be avoided. The HgCdTe growth with the MOCVD technique was more extensively presented in Refs [21][22][23][24].…”

Photoluminescence in Mercury Cadmium Telluride – a Historical Retrospective. Part II: 2004–2022

“…FWHMs of MOCVD-grown films were much larger (~30 meV), and the EPL of the latter at T > 100 K exceeded the calculated bandgap of the material with the corresponding composition. This, and the large FWHMs of the PL peaks for these films were attributed to the specifics of growth technology, the so-called 'Interdiffusion Multilayer Process', where very thin CdTe and HgTe layers are deposited consequently and interdiffuse as the growth proceeds [113]. For other types of material at low temperatures EPL was smaller than the calculated Eg, which was indicative of the effect of compositional fluctuations.…”

Research on Electro-Optical Characteristics of Infrared Detectors with HgCdTe Operating at Room Temperature

“…Growth was carried out in 2–in, epi-ready, semi-insulating (100) GaAs substrates. A description of the MOCVD system and the growth process was presented in our previous papers [ 14 , 15 ]. The classical N + / π / P + structure for IR detection includes a lightly doped p -type ( π ) semiconductor absorber with the energy gap corresponding to wavelengths in the SWIR, MWIR, and LWIR ranges.…”