EFFECT OF ETCHING TIME ON PHOTOLUMINESCENCE AND SURFACE CONDUCTIVITY OF POROUS SILICON

Abstract

Recently, porous silicon (PS) gains a lot of research interest with its potential applications in optoelectronics, flat panel displays technology, and chemical sensor. In this work, PS was chemically etched on p-type silicon (Si) wafer by hydrofluoric acid (HF) with 40% nitric acid (HNO3) concentration at different etching time. The PS has porosity dependent on etching time in the range (38-60) % that gives orange-red photoluminescence (PL) between 657 nm to 661 nm. The PL intensity increases and the peak wavelength shows slight blue shift as etching time increases. The energy gap obtained are higher than pure Si (1.11eV). Meanwhile, the conductivity of the PS decreases as the porosity and energy gap increase.