Laser microprocessing of wide bandgap materials

Abstract

Laser direct-write and doping technique (LDWD) is used to introduce variations in electric properties of wide band gap materials such as SiC and diamond. Conductive, p-type doped, n-type doped and insulative tracks are created on different diamond and SiC substrates using this method. The effects of various processing parameters such as laser-matter interaction time, number of repeated exposures, and type of irradiation environment are investigated. SEM, SIMS, XPS and Raman spectroscopy are used to study the effect of laser irradiation on the microstructure, chemical binding and to obtain dopant depth profile in the substrates, respectively. LDWD technique proved to enhance the dopant (nitrogen) diffusivity into SiC resulted in a diffusion coefficient (available in paper)that is four orders of magnitudes faster than the reported value (5 x 10-12 cm2s-1). Process modeling is conducted to study the atomistic of laser-doping process and to utilize laser irradiation to increase both dopant penetration and concentration. Laser doping of nitrogen alters the Raman spectrum of the 4H-SiC suggesting that Raman spectroscopy can be used as a non-contact method to characterize the laser-doped SiC.