In this work, the porous silicon was prepared by using stain etching in HF-HNO3 at
different etching times. Then Rapid Thermal Oxidation (RTO) processes were used for
surface treatment at different temperature and oxidation time to enhancement sample
properties. Fourier Transforms infrared (FTIR) spectrum exhibit the formation of SiHx
(x=1, 2) and Si-O bonds which indicate the present of porous structure and formation of
oxidation porous layer. The Capacitance – Voltage characteristics reveal that effective
carrier density is 36*1015 cm-3 for sample etching time at 2min, while there was a
change from (37.8*1015 to 45.7*1015) cm-3 for sample oxidation at different oxidation
temperature (373 – 973)K and from (38.2*1015 to 40*1015) cm-3 for sample oxidation at
different oxidation time (0.5 – 3.5)min. Also the porosity was (45.56%) for PS/p-Si
etching at 2min while reduce from (45% to 35.4%) with oxidation temperature, and from
(44.2% to 40.5%) with oxidation time. From photocurrent characterized, that the
photosensitivity for PS/p-Si structure is better where etching time at 2min, and its 0.2545
A/W at 370nm, and it increased after Rapid Thermal Oxidation (RTO) from (0.34 to
0.44) A/W with different oxidation temperature, and changed from (0.35 to 0.34) A/W
with different oxidation time, so that sandwich hetrojunction exhibit good efficiency