Product Code: ICA10_M309

Effect of Laser Irradiation Passes for Fabricating Mid-Wave Infrared Silicon Carbide Detectors
Authors:
Geunsik Lim, CREOL, University of Central Florida; Orlando FL USA
Tariq Manzur, Undersea Warfare Electromagnetic Systems Development; Newport RI USA
Aravinda Kar, CREOL, University of Central Florida; Orlando FL USA
Presented at ICALEO 2010

Doping is one of the challenges for silicon carbide (SiC) device fabrication due to its hardness, chemical inertness and the low diffusion coefficient of most impurities. A laser doping technique is chosen to dope 4H-SiC by gallium which is incorporated into the semiconductor as p-type dopants. The substrate is simultaneously heated with a continuous wave Nd:YAG laser of wavelength 1064 nm under the laser power, focal length, laser beam diameter and micro-stage speed were 10.5 W, 150 mm, 200 m and 0.8 mm/sec respectively using metal-organic dopant precursor. The gallium dopant profile in the laser-doped SiC wafer is obtained by secondary ion mass spectroscopy and the corresponding gallium diffusion coefficient under laser processing parameters is calculated. The laser doping of gallium in 4H-SiC with more laser irradiation passes results in a deeper dopant depth and higher dopant concentration than with less irradiation passes. The maximum concentration of Ga in SiC wafer surface with 4 time of laser irradiation passes is found to be 4.010^20 cm-3, which is two orders of magnitude higher than the reported value (6.010^18 cm-3) and the dopant depth is approximately 400 nm. The dopant diffusivity is calculated as a function of temperature at different depths of the wafer based on measured dopant concentration profile. The pre-exponential diffusion constant and the activation energy are determined by the diffusivity variation as a function of temperature. These data revealed enhanced solid solubility exceeding the equilibrium solubility limit.