Growth and characterization of Indium-doped silicon for extrinsic IR detectors

Experimental growth and characterization studies of extrinsic indium-doped silicon for 3- to 5-µm focal-plane array applications have been carried out. Large, 2- and 3-in-diameter, -oriented indium-doped silicon crystals were prepared by Czochralski crystal pulling. The growth conditions affecting crystalline perfection, maximum dopant concentration and uniformity, and the residual shallow acceptor impurity content in grown crystals were investigated. In addition, effects of carbon content on the concentration of the 0.11-eV defect level in indium-doped silicon have been studied. The results demonstrate that near dislocation-free crystals containing indium concentrations up to 5 × 10
¹⁷
cm
^-3
can be achieved at low growth rates to delay the onset of constitutional supercooling, while unwanted boron and aluminum impurities can be maintained at levels approaching 1 × 10
¹³
cm
^-3
, when high purity synthetic-quartz crucibles are utilized to minimize melt contamination. Phosphorus-compensated indium-doped infrared (IR) detector performance and test photodetectors show peak responsivities up to 10 A/W (5.9 µm, 1000 V/cm, 50 K). Monolithic CCD test structures fabricated on Czochralski indium-doped silicon substrates show lower responsivities, however, due to detrimental effects of high-temperature CCD processing.