VARIABLE ENERGY GAP DEVICES

Fabrication and evaluation of variable energy gap structures of two categories was conducted; shallow devices with 1 to 3 microns of sur face GaP, and deep devices of 6 to 40 microns depth. Shallow variable gap devices exhibited essentially equal photovoltaic properties as sin gle gap conventional devices, and demonstrate ad vantages in ruggedness, spectral response, and a numerically small temperature performance. Initial deep variable gap structures indicated severe compensation from diffusion of impurities during the phosphorus diffusion. Source of these impurities was determined to be the phosphorus. Recent devices fabricated with high purity phosphorus produced competitive, although lower, photovoltaic properties. Significant spectral response differences were observed in these devices. Informative zinc diffusion studies and data are presented. A proposed method of quick, high tem perature zinc diffusion is discussed. Evaluation of diode characteristics, spectral response, photovoltaic properties and temperature performance is reported. GaP synthesis by two methods was achieved and described. Original contains color plates; all DDC repro ductions will be in black and white. Original may be seen in DDC Hq.