Molecular Beam Epitaxial Growth of Al-doped ZnMgO Alloy Films for Modulation-doped ZnO/ZnMgO Heterostructures

概要

論文の詳細を見る
In this paper, we describe the characteristics of Al-doped $n$-type Zn1-xMgxO alloy films grown on $a$-plane sapphire substrates by molecular beam epitaxy, and the application of the films in modulation-doped ZnO/Zn1-xMgxO quantum wells (QWs). The results of Hall measurement for the Al-doped Zn0.8Mg0.2O alloy films revealed an excellent doping efficiency that the resistivity at 300 K decreased from $3.8\times 10^{-1}$ $\Omega$$\cdot$cm at $1.0\times 10^{18}$ cm-3 to $8.0\times 10^{-4}$ $\Omega$$\cdot$cm at $3.5\times 10^{20}$ cm-3. Although Al doping at higher than $10^{20}$ cm-3 resulted in a reduction in intensity and a broadening of the peak width of near-band-edge emission in cathodoluminescence with an increase in absorption-edge energy induced by the Burstein–Moss shift in optical transmittance, highly $c$-axis-oriented films without rotational domains were obtained in a wide range of doping levels. Such a successful doping was also confirmed for Zn1-xMgxO alloy films with a Mg content as high as 0.4. By applying Al doping to modulation-doped ZnO/Zn0.6Mg0.4O QWs, the sheet carrier density of the ZnO well was found to be proportional to the doping level in the Zn0.6Mg0.4O barrier layer.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-06-15