1.3 mu m GaSb metal-semiconductor-metal photodetectors

Metal-semiconductor-metal photodetectors employing GaSb active regions and Al/sub 0.5/Ga/sub 0.5/Sb barrier-enhancing abrupt regions have been fabricated on InP substrates to assess the role of hole velocity and to compare with similar photodetectors made using Ga/sub 0.47/In/sub 0.53/As active region. Devices exhibit photoresponse in the 0.2-0.65 A/W range, dark currents of approximately=10/sup -6/ A at 300 K and approximately=10/sup -10/ A at 77K for 25*25 mu m/sup 2/ area, and have a voltage-sensitive 3-dB bandwidth exceeding approximately=1 GHz at 300 K and 10 GHz at 77 K. The enhanced barrier heights are estimated to be approximately=0.30 eV. The fall time continues to be the significant component of time delay; its temperature dependence indicates that the hole velocities do improve significantly at lower temperatures. The 300 K behavior appears to be dominated by defect and impurity densities, and the effects of abrupt barriers. The larger than expected dark currents are believed to result from defects associated with lattice mismatch.<>