Low frequency 1/f noise on QWIPs, nBn, and superlattice focal plane array

Abstract

Noise Equivalent Difference Temperature (NEΔT) is a standard performance metric for most infrared focal plane array (FPA) systems. The frequency bandwidth and range associated with NEΔT is normally at high frequency and it does not describe the long time noise behavior or the very low frequency noise of the FPA. Very low frequency noise measurement requires data capture that takes longer time duration and sampling interval. This study investigates low frequency noise in QWIP, nBn and LWIR n-type Complementary Barrier Infrared Detector (CBIRD) FPAs. The corner frequencies are extracted from the power spectral density (PSD) as function of frequency. The peak wavelength, quantum efficiency of QWIP detector are 6.2μm and 2%, respectively. QWIP FPA has a mean NEΔT∼25mK at an operating temperature of 65K and an integration time of 16ms. The mean QWIP PSD plot shows a corner frequency of <0.5mHz. The nBn FPA with 4μm cut off and quantum efficiency of 67 % has NEΔT∼15.6mK at an integration time ∼7.52 ms and an operating temperature of 120K. The nBn has corner frequency of >50mHz. Lastly the n-type CBIRD FPA with a 50% cutoff at 8.8μm and quantum efficiency of ∼50 % has an NEΔT∼18.6mK at an integration time of 1.86ms and operating temperature 120K. The superlattice FPA has a corner frequency ∼10mHz. The investigation of the tail on the NEΔT histogram reveals that its origin is not accounted for entirely by the high noise current, but also it needs the inclusion of lower responsivity for some pixels.