<title>HgCdTe photodiodes with state-of-the-art performance in the near- infrared spectral region</title>

Abstract

We report on the technology we are developing to produce photovoltaic devices of HgCdTe which are sensitive in the short wave region of the solar radiation and exhibiting detectivity performance close to theoretical limits imposed by the fundamental properties of the material.Photodiodes were fabricated in a p on n device configuration, where the n-type base layer acts as the absorber layer and the p-type layer is a wider band gap HgCdTe layer with a higher fraction of Cd than in the base layer.For a cut-off wavelength of 2 tm , external Quantum efficiency as high as 69% and RA value of 3xl03 ohm-cm2 at zero bias (going up to 4x104 ohm-cm2 at -lOOmV bias and up to l.5xl05 ohm-cm2 at -200mV bias) have been demonstrated at 300 K.

Progress in Infrared Photodetectors Since 2000

“…The majority of these devices were operated around liquid nitrogen temperatures (77–100 K), though there were a couple of noteworthy exceptions [19,34–37]. A few standout devices operating in the NIR and SWIR regimes, where dark currents are minimized with the corresponding larger bandgaps, were capable of functioning at elevated temperatures, up to around 250 K [24,38,39]. The fabrication method most favored for these devices was LPE, but MBE growth was growing in popularity, particularly with devices requiring large cross-sectional areas due to MBE's finer growth control.…”

High-operability SWIR HgCdTe focal plane arrays

“…Figure 21 compares the present test chip to Rockwell's room temperature RoA vs. cutoff wavelength data, and to prior implanted-junction Avyd Devices diodes from wafer 293614 [1] processed in December 2000. The figure also shows a theoretical calculation for n-side diffusion current only, radiative lifetime, a 5-micron thick absorber, and a donor doping of 1x10 15 cm -3 .…”

“…The work we report here is a continuation of our prior work [1] and entails progress we have achieved in the optimization of our detector fabrication approach to yield quantum efficiency (QE) at the theoretical limits, and demonstration of 256x256 Focal Plane arrays with a 2.1 micron cutoff wavelength with NEI operability greater than 97% and QE operability in excess of 99.8% at 250 K. With our on going work in improving the carrier lifetime in the starting material, there is much potential for further improvement in the R 0 A performance and therewith the detectivity.…”