Khoskhlagh, Arezou | Search NASA

NASA NTRS2012

Inductively Coupled Plasma Etching for Delineation of InAs/GaSb Pixels

We developed 320x256 Complimentary Barrier Infrared (CBIRD) focal plane array (FPA) for long wave infrared (LWIR) imaging application. The FPA layers grown by molecular beam epitaxy (MBE) had 300 periods 1.9 micro m thick absorber. The CBIRD arrays showed the mean dark current density of 2.2 x 10(exp -4) A/cm2, when 128 mV bias voltage was applied. The long wave cut off was observed at 8.8 micrometers at the 50% peak and the maximum quantum efficiency was 54% at 5.6 micrometers. The arrays had 81% fill factor with 97% operability with noise equivalent difference temperature (NE(delta)T) of 18.6 mK and a mean detectivity of D*=1.3 x 10(exp 11) Hz(exp 1/2)/W.

InAs/GaSb↗

NASA NTRS2012

320 x 256 Complementary Barrier Infrared Detector Focal Plane Array for Long-Wave Infrared Imaging

A 320 x 256 Complementary Barrier Infrared (CBIRD) focal plane array for long-wavelength infrared (LWIR) imaging is reported. The arrays were grown by molecular beam expitaxy (MBE) with a 300 period 1.9 um thick absorber. The mean dark current density of 2.2 x 10-4 A/cm2 was measured at an operating bias of 128 mV with a long wavelength cutoff of 8.8 ?m observed at 50% of the peak. The maximum quantum efficiency was 54% measured at 5.6 ?m. Operating at T = 80K, the array yielded an 81% fill factor with 97% operability. Good imagery with a mean noise equivalent different temperature (NE?T) of 18.6 mK and a mean detectivity of D* = 1.3 x 1011 cm-Hz1/2/W was achieved. The substrate was thinned using mechanical lapping and neither an AR coating nor a passivation layer was applied. This article provides the details of the fabrication process for achieving low-dark current LWIR CBIRD arrays. Discussion for an effective hard mask for excellent pattern transfer is given and appropriate mounting techniques for good thermal contact during the dry etching process is described. The challenges and differences between etching large 200 ?m test diodes and small 28 ?m FPA pixels are given.

Focal Plane Arrays (FPA)↗