화학공학소재연구정보센터
Current Applied Physics, Vol.4, No.6, 679-684, 2004
Development of a novel high speed (electron-mobility) epi-n-ZnO thin films by L-MBE for III-V opto-electronic devices
Intrinsic epitaxial zinc oxide (epi-ZnO) thin films were grown by laser-molecular beam epitaxy (L-MBE), i.e., pulsed laser deposition (PLD) technique using Johnson Matthey "specpure"-grade ZnO pellets. The effects of substrate temperatures on ZnO thin film growth, electrical conductivity (Q), mobility (p) and carrier concentration (n) were studied. As well as the feasibility of developing high quality conducting oxide thin films was also studied simultaneously. The highest conductivity was found for optimized epi-ZnO thin films is sigma = 0.06 x 10(3) ohm(-1) cm(-1) (n-type) (which is almost at the edge of semiconductivity range), carrier density n = 0.316 x 10(19) cm(-3) and mobility mu = 98 cm(2)/V s. The electrical studies further confirmed the semiconductor characteristics of epi-n-ZnO thin films. The relationship between the optical and electrical properties were also graphically enumerated. The electrical parameter values for the films were calculated, graphically enumerated and tabulated. As a novelty point of view, we have concluded that without doping and annealing, we have obtained optimum electrical conductivity with high optical transparency (greater than or equal to95%) for as deposited ZnO thin films using PLD. Also, this is the first time that we have applied PLD made ZnO thin films to iso-, hetero-semiconductor-insulator-semiconductor (SIS) type solar cells as transparent conducting oxide (TCO) window layer. We hope that surely these data be helpful either as a scientific or technical basis in the semiconductor processing. (C) 2004 Elsevier B.V. All rights reserved.