Effect of dislocations on VLWIR HgCdTe photodiodes

• Published in: Journal of electronic materials Vol. 36; no. 8; pp. 1068 - 1076
• Main Authors: PARODOS, T, FITZGERALD, E. A, HU, S, REINE, M, LOVECCHIO, P, CASTER, A, TOBIN, S, MARCINIEC, J, WELSCH, J, HAIRSTON, A, LAMARRE, P, RIENDEAU, J, WOODWARD, B
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01-08-2007; Springer Nature B.V
• Subjects: Applied sciences; Cadmium telluride; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities: doping, implantation, distribution, concentration, etc; Diodes; Electronics; Exact sciences and technology; Infrared radiation; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular beam epitaxy; Optoelectronic devices; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; LPE; dislocations; Hybridization; Thin film; Dislocation; Dislocation density; Energy gap; Etch pit; VLWIR; Cadmium tellurides; Mismatch lattice; Dark current; Illumination; Mercury tellurides; HgCdTe; Double layers; Passivation; Focal plane arrays; misfit; Photodiode; Photodetector; Engraving; EPD; Property structure relationship; Heterostructures
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-007-0173-x

The effects of dislocations on very-long-wavelength infrared (VLWIR) HgCdTe photodiodes (cutoff wavelength > 14 mum at 40 K) have been determined experimentally and analyzed. The photodiodes are in the back-illuminated configuration, fabricated from HgCdTe p-on-n double-layer heterostructure (DLHJ) films grown at BAE Systems by liquid phase epitaxy (LPE) onto lattice-matched (111) CdZnTe substrates. Arrays were hybridized to silicon ROICs to form focal plane arrays (FPAs). After characterization for dark current and response, the arrays were dehybridized and stripped of their metals and passivation layers. Dislocations were revealed using a Hahnert and Schenk (H&S) etch. Pixel traceability was maintained throughout the analysis, permitting one-to-one correlation between photodiode performance and dislocation density measured within that photodiode. We found that response and dark current were correlated to etch pit density (EPD), which we assumed to be equal to dislocation density. Our results support earlier dislocation studies on larger-bandgap HgCdTe, which showed response was only weakly impacted by EPD, while dark current was strongly affected by EPD. Measured EPD values ranged from low 10 to low 10 cm. Potential causes for this range in EPD are discussed.