Dopant profiles in heavily doped ZnO

作者：Claflin Bruce^*; Leedy Kevin D; Look David C

来源：Optical Engineering, 2013, 52(5): 053801.

DOI：10.1117/1.OE.52.5.053801

• ZnO
• Ga doping
• x-ray photoelectron spectroscopy
• composition
• Hall effect

X-ray photoelectron spectroscopy (XPS) is used to compare the composition as a function of depth of as-grown zinc oxide (ZnO) films heavily doped with Ga and similar samples annealed in air for 10 min at 600 degrees C, with particular attention given to the near-surface region. Films are grown by pulsed laser deposition (PLD) using a ZnO target containing 3 wt% Ga2O3. Electrical properties of these samples are determined from temperature-dependent Hall-effect measurements. The as-grown film has the following characteristics: (1) similar to 1: 1 Zn:O ratio with a Ga concentration of similar to 3.3 at %; (2) no excess Ga in the near-surface region; and (3) excellent electrical characteristics: rho = 2.42 x 10(-4) Omega-cm, n = 8.05 x 10(20) cm(-3), and mu = 32.1 cm(2)/V-s-s at 300 K. For the annealed sample: (1) the Zn: O ratio remains similar to 1: 1, but the Ga concentration is similar to 3 at %, which is similar to 10% lower than in the as-grown film; (2) similar to 7 at % Ga is measured in the near-surface region; and (3) a significant increase in resistivity to rho = 0.99 Omega-cm, n = 1.97 x 10(18) cm(-3), and mu = 3.2 cm(2)/V-s at 300 K. Analysis of the O chemical shift suggests formation of a mixed ZnO/Ga2O3 surface layer %26lt;= 5-nm-thick accounts for the observed changes in the Ga profile after annealing. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

• 出版日期2013-5