Implementation of P-type black silicon with high aspect ratio for optoelectronics applications

Abstract

Black Silicon (BSi) is a semiconductor with a surface modified to get a very low reflectivity and correspondingly high absorption of visible light. P-type <100> silicon wafers were used to prepare very low reflecting samples. These samples may use as substrates in optoelectronic applications. Electrochemical etching at different etching current, and time were applied. B-silicon is chemically equal to normal silicon, differs in surface treatment that changes a morphology. This special morphology is demanded for absorption enhancement which involves maximum light absorption. Surface roughness is done by texturing or trenching a silicon wafer surface. As these structures are in place, and as they are small enough, incident light will be more absorbed and less reflected, this is what gives black silicon its name. BSi was characterized by (FESEM), structural analysis indicates that BS layers were formed. The porosity was in the range of (10–40) % and it is dependent on etching time and etching current value. Etching density is 0.1073/mm2. Reflection analysis shows satisfying minimum reflectivity spectrum with the intensity of peaks decrease and red shifted with increasing the etching current. A peak of the Photoluminescence ranges about 360 nm, PL peaks are blue shifted and proportional to etching current. The band gap energy ranged from 2 to 3.4 eV, it is affected with porous morphology and directly proportional to etching current values