HgZnTe for very long wavelength infrared applications

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HgZnTe has been of considerable interest in the last few years as an alternative infrared (IR) detector material to HgCdTe because of HgZnTe’s greater mechanical hardness, higher Hg vacancy formation energies, and other desirable properties which may lead to greater producibility (yield) and reliability (operation life). We are developing very long wavelength IR (VLWIR) HgZnTe detectors (17 μm at ≥65K) for longterm Earth Observing System NASA missions. In recent months we have been able to achieve, nearly routinely, outstanding quality HgZnTe on lattice-matched substrates (Cd0.84Zn0.16Te). By careful screening of substrate quality and refinement of the growth system and growth parameters, we overcame previous melt retention problems observed when using these high Zn% substrates. X-ray rocking curve widths (full width at half-maximum) as narrow as 26 arc-sec (for a 1×8 mm spot) for these epilayers have been achieved which is comparable to that for the best HgCdTe ever reported. In addition, we have, for the first time, fabricated and demonstrated high performance VLWIR (λco>17 μm at 80K) photoconductors made from liquid phase epitaxy HgZnTe which exhibit near background limited performance (peak D* up to 1011 cm(Hz)1/2/W) at high background. From these device results we see a clear correlation between the layer/substrate lattice match and the resulting device performance.