N-type Black Silicon with high aspect ratio for-optoelectronic applications
Black Silicon (BSi) is a semiconductor with a surface modified to get a very low reflectivity and correspondingly high absorption of incident light.
In this study, n-type <100> porous silicon wafers were prepared as a very low reflecting substrates for utilizing in optoelectronic devices. Etching parameters were the current density and the etching time.
The Photo- electrochemical Etching technique(PEC) at room temperature was used to treat the samples. Different etching times and different etching currents were examined. investigations of structural and optical properties of samples were demonstrated.
BSi was characterized by (FESEM). structural analysis indicates that many etched layers were formed within the surface. The porosity was in the range of (11-31) % and it is dependent on etching time and etching current value. Etching density was 0. 1073/mm2.
Reflection analysis shows satisfying minimum reflectivity spectrum, peaks intensity was decreased sharply and blue shifted with increasing the etching current. The peak of the Photoluminescence was about 360 nm. The band gap energy was (3.54 eV), it is affected with the porous morphology and directly proportional to the etching current values.