The Effect of Wide-Bandgap Cap Layer on the Performance of Metal-Semiconductor-Metal Photodetectors

다국어 초록 (Multilingual Abstract)

The effect of wide-bandgap Schottky-barrier-enhancement layers on the performance of metal-semiconductor-metal photodetectors (MSMPDs) has been studied. The detection threshold voltage of an MSMPD with a Schottky-barrier-enhancement cap layer is much lower and much more dependent on the light intensity than an MSMPD without this layer due to carrier capture at the heterointerface. The threshold voltage increases significantly as the light intensity is increased, and the intensity-dependence is larger for an MSMPD with a larger band-discontinuity. The quantum efficiencies of the cap-layered MSMPDs drops significantly under pulse-operation. The efficiencies of a GaAs-based MSMPD with a lattice-matched AlGaAs cap layer and an InGaAs-based MSMPD with a lattice-matched InAlAs cap layer were measured to be 0.57 and 0.39, respectively, for devices with a Ti/Au finger width/gap of 1 ㎛/1 ㎛. The loss of efficiency by the incorporation of a cap layer has been found to be proportional to the dominant band-discontinuity at the interface. The inclusion of a cap layer was found to have no significant effect on the 3-dB bandwidth of the photodetectors. The authors wish to acknowledge the financial support of the Korea Research Foundation made in the program year of 1997.

목차 (Table of Contents)

• Abstract
• Ⅰ.INTRODUCTION
• Ⅱ.DEVICE FABRICATION
• Ⅲ.MEASUREMENT SETUP
• Ⅳ.DIRECT-CURRENT CHARACTERISTICS
• Ⅴ.TEMPORAL CHARACTERISTICS
• Ⅵ.CONCLUSIONS
• REFERENCES