Laser doping and metallization of wide bandgap materials: silicon carbide, gallium nitride, and aluminum nitride

A laser direct write and doping (LDWD) system is designed and utilized for direct metallization and selective area doping in different SiC polytypes, GaN and in dielectrics including AlN. Laser direct metallization in 4H- and 6H-SiC generates metal-like conductive phases that are produced as both rectifying and ohmic contacts without metal deposition. Nd:YAG (λ = 532, 1064 nm) nanosecond pulsed laser irradiation in SiC induces carbon-rich conductive phases by thermal decomposition of SiC while UV excimer (λ = 193 nm) laser irradiation produces a silicon-rich phase due to selective carbon photoablation. Linear transmission line method (TLM) pattern is directly fabricated in single crystals SiC by pulsed laser irradiation allowing characterization of the laser fabricated metal-like contacts. Activation of a self focusing effect at the frequency doubled Nd:YAG laser irradiation (λ = 532 nm) allows to fabricate buried metal like contacts in SiC wafers while maintaining their device-ready surface condition.; Gas immersion laser doping (GILD) and laser doping from a molten precursor are utilized to dope both GaN and SiC. Trimethylaluminum (TMAl) and nitrogen are the precursors used to produce p-type and n-type doped SiC; respectively. Nd:YAG and excimer laser nitrogen doping in SiC epilayer and single crystal substrates increases the dopant concentration by two orders of magnitude and produces both deep (500–600 nm) and shallow (50 nm) junctions, respectively. Laser assisted effusion/diffusion is introduced and utilized to dope Al in SiC wafers. Using this technique, a150 nm p-type doped junction is fabricated in semi-insulating 6H- and n-type doped 4H-SiC wafers. Laser-induced p-type doping of Mg in single crystal GaN is conducted using Bis-magnesium dihydrate [Mg(TMHD)₂]. Mg concentration and penetration depth up to 10 20–1021 cm−3 and 5μm, respectively are achieved using various laser doping techniques.; Laser direct writing and doping (LDWD) is a viable method for processing wide bandgap materials for electronics and optoelectronics devices applications. It effectively reduces the number of fabrication steps and allows for selective area doping and direct metallization without metal deposition.