Long-Wavelength Germanium Photodetectors by Ion Implantation

Abstract

ABSTRACTExtrinsic far-infrared photoconductivity in thin high-purity germanium wafers implanted with multiple-energy boron ions has been investigated. Initial results from Fourier transform spectrometer(FTS) measurements have demonstrated that photodetectors fabricated from this material have an extended longwavelength threshold near 192μm. Due to the high-purity substrate, the ability to block the hopping conduction in the implanted IR-active layer yields dark currents of less than 100 electrons/sec at temperatures below 1.3K under an operating bias of up to 70mV. Optimum peak responsivity and noise equivalent power(NEP) for these sensitive detectors are 0.9A/W and 5×10−16 W/Hz1/2 at 99μm, respectively. The dependence of the performance of devices on the residual donor concentration in the implanted layer will be discussed.