FORWARD-BIAS CHARACTERISTICS OF SI BIPOLAR JUNCTIONS GROWN BY MOLECULAR-BEAM EPITAXY AT LOW-TEMPERATURES

Forward-bias current-voltage characteristics of molecular beam epitaxy grown Si p+-i-n+ junctions have been determined at room temperature. At small widths of the i zone (L(i) = 5 and 10 nm) band-to-band tunnel ing with a maximum peak-to-valley ratio of two is observed. Up to L(i) = 30 nm (trap assisted) forward-bias tunneling is apparent with satur ation tunneling current densities somewhat lower than in p-n junctions at comparable widths of the space-charge region W(SCR)(0). For L(i) > 30 nm and T(g) = 500-degrees-C growth temperature surface recombinati on dominates the low bias range. At L(i) = 35 nm and T(g) = 325-degree s-C, both surface and bulk recombination is observed. We found evidenc e that Si molecular beam epitaxy layers grown at this low temperature get an increasing density of crystalline defects with growing thicknes s.