Laser-induced local activation of Mg-doped GaN with a high lateral resolution for high power vertical devices

Abstract

A method for laser-induced local p-type activation of an as-grown Mg-doped GaN sample with a high lateral resolution is developed for realizing high power vertical devices for the first time. As-grown Mg-doped GaN is converted to p-type GaN in a confined local area. The transition from an insulating to a p-type area is realized to take place within about 1–2 μm fine resolution. The results show that the technique can be applied in fabricating the devices such as vertical field effect transistors, vertical bipolar transistors and vertical Schottkey diode so on with a current confinement region using a p-type carrier-blocking layer formed by this technique.

Impact of Mg level on lattice relaxation in a p-AlGaN hole source layer and attempting excimer laser annealing on p-AlGaN HSL of UVB emitters

“…Another group used localized effects of excimer laser irradiation using a KrF excimer laser pulse on metal contacts grown on n-type and p-type GaN as well as for the Mg activation in the p-GaN [35]. Similarly, Kurose et al introduced a laser-induced local activation (LILA) process, which was developed for the first time to allow the preparation of locally activated p-type regions without any damage or dopant migration in p-GaN [36]. LEEBI, LILA and excimer laser annealing (ELA) techniques show a promising future for localized activation of Mg atoms, suppression of unwanted impurities and crystal healing in both p-GaN [34][35][36] and p-AlGaN (this work).…”

Laser-induced activation of Mg-doped GaN: quantitative characterization and analysis

“…In a recent paper [6], Kurose et al provided experimental proof of the effectiveness of laser-induced local activation of Mg-doped GaN, thus confirming the important of this technology for the fabrication of vertical and lateral GaN devices, as an alternative to regrowth and ion implantation. This recent report demonstrated the importance of laser-based p-GaN activation, but did not give further information on the physics of laser-based p-GaN activation, and on how to tune the process parameters to optimize the effectiveness of the treatment.…”

“…For this reason, alternative methods are explored, with the aim of obtaining a good activation rate, and-whenever possible-spatially-resolved activation. One of the proposed methods is laser activation [6][7][8]: the idea is to use a short-wavelength excimer laser with ns-range pulses to irradiate the semiconductor in controlled atmosphere. The energy released by the short pulses results in a localized and effective dissociation of the Mg-H complexes, with consequent increase in p-GaN conductivity.…”

Highly Transparent p‐AlGaN‐Based (326–341 nm)‐Band Ultraviolet‐A Light‐Emitting Diodes on AlN Templates: Recent Advances and Perspectives

“…To reduce the operating voltages as well as to enhance the hole injection toward the MQWs, we need highly conductive p-AlGaN HSL including p-AlGaN contact layer as well as p-MQB EBL, by using Al-graded polarizability effect assisted by rapid-thermalannealing (RTA). [49,[52][53][54][55][56][57][58] The hole concentration "p" depends on the acceptor energy level in the exponential fashion as:p % exp À E A kT À Á , where k: Boltzmann constant, T: absolute temperature, and E A : activation energy level (ranging in 240-590 meV) in the p-AlGaN HSL, shown in Figure 10A. [49] .…”

“…Recently, ELA of ion implanted semiconductor materials [54] has been received a great interest within the semiconductor community for its possible application to the formation of ultra-shallow junctions in semiconductor devices. [56,58] Historically speaking, low-energy-electron-beam irradiation (LEEBI) treatment, [55] ELA treatment, [56] and laserinduced local activation (LILA), [57] were performed for the activation of Mg-dopants in the p-GaN as well as for the activation of n-/p-contact on p-/n-GaN contact layers. Recently, we successfully achieve high hole density in the Al-graded p-AlGaN HSL for UVB emitters, where the hole-trap level appeared to have been effectively suppressed by ELA treatment, and a reasonably improved hole concentration up to 2 Â 10 16 cm À3 was generated with reduced resistivity of 24 Ω cm by polarization-assisted mechanism in the lightly polarized n-AlGaN HSL at RT.…”