Control and growth of middle wave infrared (MWIR) Hg(1−x)CdxTe on Si by molecular beam epitaxy

Abstract

Middle wave infrared (MWIR) HgCdTe p-on-n double-layer heterojunctions (DLHJs) for infrared detector applications have been grown on 100-mm Si (112) substrates by molecular beam epitaxy (MBE) for large format 2,560 ϫ 512 focal plane arrays (FPAs). In order to meet the performance requirements needed for these FPAs, cutoff and doping uniformity across the 100-mm wafer are crucial. Reflection high-energy electron diffraction (RHEED), secondary ion mass spectrometry (SIMS), Fourier transform infrared spectrometry (FTIR), x-ray, and etch pit density (EPD) were monitored to assess the reproducibility, uniformity, and quality of detector material grown. Material properties demonstrated include x-ray full width half maximum (FWHM) as low as 64 arc-sec, typical etch pit densities in mid-10 6 cm Ϫ2 , cutoff uniformity below 5% across the full wafer, and typical density of macrodefects Ͻ 1000 cm Ϫ2 . The detector quality was established by using test structure arrays (TSAs), which include miniarray diodes with the similar pitch as the detector array for easy measurement of critical parameters such as diode I-V characteristics and detector quantum efficiency. Typical I-V curves show excellent R o A products and strong reverse breakdown characteristics. Detector quantum efficiency was measured to be in the 60-70% range without an antireflection coating.

LWIR HgCdTe Detectors Grown on Ge Substrates

“…As demonstrated in our previous work we typically observe an EPD in the mid 10 6 cm -2 range for MWIR HgCdTe/Si layers. 4 In this work the EPD of our LWIR structure grown on Si presents the same density of pits, i.e., in the mid 10 6 cm -2 range. It was hoped that by using Ge as substrate we would obtain lower EPD on the same structure due to the lower lattice mismatch and similar coefficient of thermal expansion between the substrate and grown material.…”

“…The ZnTe/CdTe buffer layer and HgCdTe detector structures were grown without wafer removal from the MBE system; a more detailed procedure for growth was reported previously. 4 All growth was performed in a rotating manipulator. Each growth began with a buffer layer consisting of about 0.5-lm-thick ZnTe and 7-lm-thick CdTe.…”

Flexibility of p–n Junction Formation from SWIR to LWIR Using MBE-Grown Hg(1–x)Cd x Te on Si Substrates

“…A. Woollam Co., Inc. to control material composition in real time. 3 By using FTIR we have previously shown how powerful the MBE technique is by demonstrating in a larger production MBE system that very large-area devices can be routinely obtained with excellent lateral composition uniformity. For a full 150-mm Si wafer, 4 the uniformity is better than 1%.…”

“…However, this higher value of EPD on structures grown on Si substrates has not compromised the performance of detectors in the mid-long infrared spectrum. 3,12 n-AND p-TYPE DOPING One of the most important properties of a semiconductor material is the ability to incorporate both types of electrical carriers, n and p. Additionally, the ability to achieve an abrupt transition between the dopant species is important. The MBE technique and the HgCdTe system are a good match for Flexibility of p-n Junction Formation from SWIR to LWIR Using MBE-Grown Hg (1-x) Cd x Te on Si Substrates developing optoelectronics devices in the infrared spectral region.…”

Bi-color and dual-band HgCdTe infrared focal plane arrays at Defir

“…MBE is today a very mature technique to successfully achieve 3 rd generation detectors such as multispectral detectors, and allows the fabrication of low cost large wafers (more than 4'') on heterosubstrates (germanium, silicon). [5,6] In this paper we present examples of design and characterization of two different architectures of FPA based on two different concepts. The first one is the classical npn back to back MCT photodiode structure that operates within the MWIR in sequential mode with one connexion per pixel.…”