Defect mitigation of electronic devices is conventionally achieved using thermal annealing. To mobilize the defects very high temperature is necessary. Since thermal diffusion is random in nature, the process may take a prolonged period of time. In contrast, we demonstrate a room temperature annealing technique that takes only a few seconds. The fundamental mechanism is defect mobilization by atomic scale mechanical force originated from very high current density but low duty cycle electrical pulses. The high energy electrons lose their momentum upon collision with defects, yet low duty cycle suppresses any heat accumulation to keep the temperature at ambient. For 7×105 A/cm2 pulsed current, we report approximately 26% reduction in specific on-resistance, 50% increase of rectification ratio with lower ideality factor and reverse leakage current for as-fabricated vertical geometry GaN p-n diodes. We characterized microscopic defect density of the devices before and after the room temperature processing to explain the improvement in the electrical characteristics. Raman analysis reveals improvement in crystallinity of the GaN layer and approximately 40% relaxation of any post-fabrication residual strain compared to the as-received sample. Cross-sectional transmission electron microscopy (TEM) images and geometric phase analysis (GPA) results of high-resolution TEM (HRTEM) images further confirm the effectiveness of the proposed room temperature annealing technique to mitigate defects in the device. No detrimental effect, such as diffusion and/or segregation of elements, is observed as a result of applying high density pulsed current, as confirmed by energy dispersive X-ray spectroscopy (EDX) mapping.
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- Applied Physics Express
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- Medium: X
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- National Science Foundation
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