The characteristics of the porous Si layer filled with a metal using pulsed electroplating system

초록

Porous silicon(PS) has recently aroused considerable interest, especially in view of photoluminescence(PL) and electroluminescence(EL) properties. Many researchers are trying to find out the mechanism of photoluminescence and electroluminescence in PS layer to optimize the optical properties. In making EL devices, it is important to make good contact between PS and metal. We deposited metals into pores using the forward pulsed current source. The PS samples studied here were prepared by electrochemical anodization of boron doped p-type (1-15Ω㎝ in resistivity) Si(100) wafers at a constant current density. The current density were varied from 5 to 50 mA/cm2. An electroplating system with forward pulsed-signal current sources was used to deposit several metals. Pulsed signal current sources was used to obtain smaller grain size and good morphology of metal layer. Also metals deposited by immersion plating on the PS layer. Two samples prepared by different methods were compared. The metal layers on PS were investigated by XPS, SEM, AES and the change in the bonding state of the Si-Hx, and the Si-O-Si using Fourier Transform-Infrared Spectroscopy(FTIR). Also investigated the filling of pores by metals using RBS. Electroplating into the PS layer using pulsed current sources was studied and the results were compared with those of immersion plating. There is nearly no change of PL intensity between the two samples, but significant difference in EL Intensity.