The U-shaped photodetector structure optimization by increase random pyramid size

Abstract

This paper purpose the fabrication method of U-shape metal-semiconductor-metal structure photodetector with Al/n-Si/Al materials on anisotropic wet etching. In this paper studied on 20 wt% of potassium hydroxide (KOH) and 5 wt% of Tetramethylammonium hydroxide (TMAH: (CH3)4NOH) and mixed with 34 g/l silicic acid also heating with 80 degrees Celsius. From the experiment found the best condition for fabricating the photodetector is the experiment, which uses the mixture of TMAH solution and silicic acid because it obtained the lowest aluminum layer etch rate and no alkaline ion or contaminant on a surface that able to apply with the integrated circuit. Moreover, this mixture gave a large amount of random pyramid structure on the surface also more than fabricate with KOH solution and made the light responsibility on 25,000 lux more than KOH model about 1.3 times. This result shown the big pyramid provide the light reflection lower than small pyramid that takes many effects to light absorption and photocurrent and controls the transducing performance of a photodetector.