HOLE ACCUMULATION EFFECT OF InGaAs HIGH-ELECTRON-MOBILITY TRANSISTORS WITH A 1550-nm WAVELENGTH FEMTOSECOND PULSE LASER

Abstract

InGaAs is known as a material system with high electron mobility derived from InAs and can be formed by metal organic chemical vapor deposition. The base material substrate is InP and is formed by controlling the composition ratio of In and Ga to lattice match with this InP. The bandgap energy Eg of InGaAs is 0.87 eV, and photoelectric conversion of 1550-nm light, which is a communication wavelength band, can be executed. Therefore, it is now used as a detector material in optical communication technology. In this study, we investigated the photoresponsive properties of InGaAs high-electron-mobility transistors (HEMTs) with simultaneous utilization of photoresponse characteristics and high-frequency response characteristics of this InGaAs crystal. A 1550-nm wavelength femtosecond pulse laser (with a pulse width of 100 fs and a period of 50 MHz) was coupled with DC light with a wavelength of 1480 nm and irradiated from the InGaAs HEMT metal electrode surface. Laser light transmitted through the side of the gate metal electrode into the device structure generates electron-hole pairs via the photoelectric effect in the InGaAs layer, and it was confirmed that the maximum drain current of 0.4 mA was reduced. A current response is detected inside the semiconductor by transporting electrons to the drain electrode side and holes to the source electrode side. Because the laser used is pulsed light, the process of generation and disappearance of electron-hole pairs were confirmed as photoresponsive properties.