1/f noise in large-area Hg1-xCdxTe photodiodes

• Published in: Journal of electronic materials Vol. 32; no. 7; pp. 633 - 638
• Main Authors: D'SOUZA, A. I, STAPELBROEK, M. G, DOLAN, P. N, WIJEWARNASURIYA, P. S, DEWAMES, R. E, SMITH, D. S, EHLERT, J. C
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01.07.2003
• Subjects: Applied sciences; Bolometer; infrared, submillimeter wave, microwave and radiowave receivers and detectors; Electronics; Exact sciences and technology; Infrared, submillimeter wave, microwave and radiowave instruments, equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Optoelectronic devices; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Ternary compound; Voltage current curve; Infrared detector; Tunnel effect; molecular-beam epitaxy (MBE); 1/f noise; Photodiode; Mid infrared radiation; Photodetector; Cut off frequency; Far infrared radiation; Near infrared radiation; Cadmium tellurides; photodiodes; Hg1-xCdxTe detectors; White noise; Dark current; Molecular beam epitaxy; Heterojunctions; Mercury tellurides; Photoelectric current; Double layers; Planar technology
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-003-0044-z

The 1/f noise in photovoltaic (PV) molecular-beam epitaxy (MBE)-grown Hg1-xCdxTe double-layer planar heterostructure (DLPH) large-area detectors is a critical noise component with the potential to limit sensitivity of the cross-track infrared sounder (CrIS) instrument. Therefore, an understanding of the origins and mechanisms of noise currents in these PV detectors is of great importance. Excess low-frequency noise has been measured on a number of 1000-*mm-diameter active-area detectors of varying 'quality' (i.e., having a wide range of I-V characteristics at 78 K). The 1/f noise was measured as a function of cut-off wavelength under illuminated conditions. For short-wave infrared (SWIR) detectors at 98 K, minimal 1/f noise was measured when the total current was dominated by diffusion with white noise spectral density in the mid-10-15 A/Hz1/2 range. For SWIR detectors dominated by other than diffusion current, the ratio, a, of the noise current in unit bandwidth in(f = 1 Hz, Vd = -60 mV, and *Df = 1 Hz) to dark current Id(Vd = -60 mV) was *aSW-d = in/Id #~ 1 x 10-3. The SWIR detectors measured at 0 mV under illuminated conditions had median *aSW-P = in/Iph #~ 7 x 10-6. For mid-wave infrared (MWIR) detectors, *aMW-d = in/Id #~ 2 x 10, due to tunneling current contributions to the 1/f noise. Measurements on forty-nine 1000-*mm-diameter MWIR detectors under illuminated conditions at 98 K and -60 mV bias resulted in *aMW-P = in/Iph = 4.16 #+ 1.69 x 10-6. A significant point to note is that the photo-induced noise spectra are nearly identical at 0 mV and 100 mV reverse bias, with a noise-current-to-photocurrent ratio, *aMW-P, in the mid 10-6 range. For long-wave infrared (LWIR) detectors measured at 78 K, the ratio, *aLW-d = in/Id #~ 6 x 10-6, for the best performers. The majority of the LWIR detectors exhibited *aLW-d on the order of 2 x 10-5. The photo-induced 1/f noise had *aLW-P = in/Iph #~ 5 x 10-6. The value of the noise-current-to-dark-current ratio, *a appears to increase with increasing bandgap. It is not clear if this is due to different current mechanisms impacting 1/f noise performance. Measurements on detectors of different bandgaps are needed at temperatures where diffusion current is the dominant current. Excess low-frequency noise measurements made as a function of detector reverse bias indicate 1/f noise may result primarily from the dominant current mechanism at each particular bias. The 1/f noise was not a direct function of the applied bias.