In situ hole doping of wide-gap semiconductors by dual-target simultaneous laser ablation: GaN and SiC epitaxial films

Abstract

Apparatus for dual-target simultaneous laser ablation deposition and in situ doping techniques have been developed to achieve p-type doping during epitaxial growth of wide-band-gap semiconductors. The apparatus has two target holders with a target-rotation mechanism and a rotation-axis adjusting mechanism to obtain homogeneously doped films. Mg-doped GaN films have been fabricated on 6H-SiC͑0001͒ and Si͑111͒ substrates in NH 3 ambient by simultaneous ablation of GaN and Mg-metal targets using two lasers. Junctions of the films with n-type substrates show a diode curve characteristic of p-n junctions, but not for junction with p-Si, indicating hole doping without further procedures. In situ p-type doping to SiC was also achieved by using SiC and Al 4 C 3 targets.

Mechanical properties of pulsed laser deposited nanocrystalline SiC films

“…Progresshas been recently made using CVD, ion beam or sputtering tech-niques [1][2][3][4][5][6][7][8]. By using the Pulsed Laser Deposition (PLD) technique,good quality SiC films that are very useful for properties investiga-tions were also synthesized [9][10][11][12][13][14]. The use of a high laser fluence, a very low residual vacuum, high purity CH4and high repetitionrates were necessary to grow the films [15].…”

Structural characterization of ultrathin Cr-doped ITO layers deposited by double-target pulsed laser ablation

“…The doping process by PLD can be accomplished by using several approaches such as ablation of a single target obtained by premixing of the materials to be deposited [30,31], ion implantation [32], dual beam method [33][34][35][36][37], dual target simultaneous PLD apparatus [38] and switching ablation among targets with different composition. It must be emphasized that the microstructure of the pellet material strongly affect the final film morphology and structural quality through the formation, distribution and density of particulates in the deposit [39][40][41][42].…”

Fabrication of GaN/ZnO bilayers on sapphire by pulsed laser ablation‐deposition

“…We studied previously fabrication of ZnO and GaN crystalline films by pulsed laser ablation-deposition (PLAD) [6,7] and found an improvement of GaN films by introduction of ZnO buffer layer on Si substrates [8,9]. Dual-targets simultaneous PLAD of Mg and GaN made in-situ p-type doping possible [10]. We have examined presently fabrication of bilayers of GaN and ZnO on Al 2 O 3 that is used for optoelectronic devices, since such heteroepitaxial multilayers may be helpful for developing devices and lowering the device cost.…”

“…2a). Preparation of the bottom GaN layer was examined in slightly wide conditions; P NH3 = 0.02-2 Pa, f = 2 or 5 Hz, and T h = 900-1150 o C, by referring previous works [9][10][11]. ZnO layer was overlaid on the GaN epitaxial layers at around optimal conditions, T h = 650 or 800 o C and P O2 = 0.5 or 2 Pa.…”

“…2 Experimental Details of the preparation of ZnO and GaN targets and fabrication procedures of their epitaxial films are described elsewhere [6][7][8][9][10]. ZnO powders are pre-sintered in flowing high purity O 2 (99.9995%) at ∼900 ºC for 2 hours.…”