MBE Growth of HgCdTe on Large-Area Si and CdZnTe Wafers for SWIR, MWIR and LWIR Detection

Abstract

Molecular beam epitaxy (MBE) growth of HgCdTe on large-size Si (211) and CdZnTe (211)B substrates is critical to meet the demands of extremely uniform and highly functional third-generation infrared (IR) focal-panel arrays (FPAs). We have described here the importance of wafer maps of HgCdTe thickness, composition, and the macrodefects across the wafer not only to qualify material properties against design specifications but also to diagnose and classify the MBE-growth-related issues on large-area wafers. The paper presents HgCdTe growth with exceptionally uniform composition and thickness and record low macrodefect density on large Si wafers up to 6-in in diameter for the detection of short-wave (SW), mid-wave (MW), and long-wave (LW) IR radiation. We have also proposed a cost-effective approach to use the growth of HgCdTe on low-cost Si substrates to isolate the growth-and substrate-related problems that one occasionally comes across with the CdZnTe substrates and tune the growth parameters such as growth rate, cutoff wavelength (k cutoff ) and doping parameters before proceeding with the growth on costly large-area CdZnTe substrates. In this way, we demonstrated HgCdTe growth on large CdZnTe substrates of size 7 cm · 7 cm with excellent uniformity and low macrodefect density.

Achieving Manufacturing Readiness for 6-Inch HgCdTe on Silicon

“…Following the conception and detail design phases for new third-generation products, a proof of concept needs to be realized (MRL/ TRL 3,4,5). At RVS this role is fulfilled by the Advanced Development Group, which handles processing and execution of new technologies in a facility located separately from the production factory.…”

“…For HgCdTe on silicon, the average macrodefect density remains less than 25 cm À2 and the range/ minimum value of HgCdTe composition and thickness uniformity remains better than 1.4%. 4 Fourier-transform infrared mapping for HgCdTe thickness, CdTe thickness, cut-on wavelength at room temperature, projected cut-off at detector temperature, and void defect mapping are all typical outputs measured for product characterization and are key ingredients in MRL 4, 5, and 6. To date, 6-inch HgCdTe-on-silicon wafers have less than 0.05 lm center-to-edge cut-off uniformity.…”

Progress in the Molecular Beam Epitaxy of HgCdTe on Large-Area Si and CdZnTe Substrates

“…In our previous paper, 2 we reported a high-quality HgCdTe growth with exceptional uniformity and ultralow defect density on 6-inch Si wafers. We also presented a methodology to take advantage of highly matured and reliable HgCdTe on Si process to tune growth conditions for HgCdTe on CdZnTe substrates.…”

“…3 Following this strategy, we successfully demonstrated highly uniform and low-defectdensity single-color HgCdTe detector growth on 7 cm 9 7 cm CdZnTe substrates and two-color longwave infrared/long-wave infrared (LWIR/LWIR) HgCdTe detector growth on 5 cm 9 5 cm CdZnTe substrates. 2 In this paper, we present the uniformity and defect density results of HgCdTe growth, for the first time, on an 8 cm 9 8 cm CdZnTe substrate. We also present the maturity of our HgCdTe growth process on large-area substrates by presenting the highuniformity and low-defect-density data of HgCdTe grown during two different growth campaigns on four 7 cm 9 7 cm CdZnTe substrates.…”

HgCdTe Growth on 6 cm × 6 cm CdZnTe Substrates for Large-Format Dual-Band Infrared Focal-Plane Arrays

“…This paper describes MBE growth of dual-band MWIR/LWIR device structures on 6 cm 9 6 cm CdZnTe substrates and examines important properties such as EPD, wafer-level uniformity of k c , and defect density using Fourier-transform infrared (FTIR) mapping and macrodefect mapping techniques described elsewhere. 3,4 Here we refer to the macrodefect density as the sum of the areal densities of voids and microvoids, generally all light-scattering objects >2 lm in size. Our initial results indicated a better HgCdTe compositional uniformity on a relatively larger 6-inch Si substrate when compared with that on a 6 cm 9 6 cm CdZnTe substrate.…”