Pulse Laser Sulfur-Hyperdoping of Germanium and High Quantum Efficiency Photodiodes

Germanium was successfully hyperdoped with sulfur by means of nanosecond pulse laser and SF6 gas. A photodiode was fabricated based on sulfur-hyperdoped germanium. Rectifying current-voltage characteristics were observed for the device. The sulfur-hyperdoped germanium photodiode showed an internal quantum efficiency close to 150% from visible to near infrared and increased to 275% for the ultraviolet region. The -3 dB bandwidth was measured to be 20 MHz. Sulfur was demonstrated to be an effective deep level dopant for realizing high-performance germanium photodiodes.