The performance of an extrinsic silicon detector array depends on achieving uniform distribution of both the major dopant and compensating impurities in the array. While in some cases uniformity can be achieved during device processing (for example, by neutron transmutation doping to control compensation), usually the uniformity must be grown in. We report the influence of changing the pull rate and rotation rate in the float zone growth of gallium-doped silicon on the resulting distribution of gallium in the crystal. The gallium distribution was monitored by etching studies and by spreading resistance and four-point probe measurements. High rotation rates and low pull rates favor higher uniformity. These results can be understood in terms of steady-state segregation theory. We also examined the effects of prolonged diffusion on originally nonuniform Si:Ga by monitoring spreading resistance and measuring Hall effect vs. temperature. Observed improvements in uniformity were consistent with diffusion theory; 16 days of diffusion at 1300°C produced marked improvement in Ga uniformity.

Date Published: 11 June 1981
PDF: 12 pages
Proc. SPIE 0285, Infrared Detector Materials, (11 June 1981); doi: 10.1117/12.965803

Published in SPIE Proceedings Vol. 0285:
Infrared Detector Materials
H. R. Riedl, Editor(s)