Effects of Thermal Annealing on the Properties of Zirconium-Doped MgxZn1-XO Films Obtained through Radio-Frequency Magnetron Sputtering.

Wen-Yen Lin,Hsien-Chin Chiu,Feng-Tsun Chien,Kuang-Po Hsueh,Jinn-Kong Sheu

doi:10.3390/membranes11050373

Abstract

Zirconium-doped MgxZn1−xO (Zr-doped MZO) mixed-oxide films were investigated, and the temperature sensitivity of their electric and optical properties was characterized. Zr-doped MZO films were deposited through radio-frequency magnetron sputtering using a 4-inch ZnO/MgO/ZrO2 (75/20/5 wt%) target. Hall measurement, X-ray diffraction (XRD), transmittance, and X-ray photoelectron spectroscopy (XPS) data were obtained. The lowest sheet resistance, highest mobility, and highest concentration were 1.30 × 103 Ω/sq, 4.46 cm2/Vs, and 7.28 × 1019 cm−3, respectively. The XRD spectra of the as-grown and annealed Zr-doped MZO films contained MgxZn1−xO(002) and ZrO2(200) coupled with Mg(OH)2(101) at 34.49°, 34.88°, and 38.017°, respectively. The intensity of the XRD peak near 34.88° decreased with temperature because the films that segregated Zr4+ from ZrO2(200) increased. The absorption edges of the films were at approximately 348 nm under 80% transmittance because of the Mg content. XPS revealed that the amount of Zr4+ increased with the annealing temperature. Zr is a potentially promising double donor, providing up to two extra free electrons per ion when used in place of Zn2+.

Highlights

The use of zinc oxide (ZnO) as a semiconductor material in thin-film transistors (TFTs) has recently received attention because of the material’s excellent electrical characteristics, its usage of a low-temperature process, and its transparency performance in comparison with conventional silicon TFTs [1,2,3]
ZnO can be alloyed with MgO to form the ternary compound MgxZn1−xO (MZO), which has a larger energy band gap than ZnO and a detection spectrum that is located in a shorter wavelength region
We investigated the thermodynamic stability of Zr-doped MZO films through Hall measurements, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS)

Summary

Introduction

The use of zinc oxide (ZnO) as a semiconductor material in thin-film transistors (TFTs) has recently received attention because of the material’s excellent electrical characteristics, its usage of a low-temperature process, and its transparency performance in comparison with conventional silicon TFTs [1,2,3]. ZnO is a II–VI compound semiconductor that has several favorable characteristics, including wide energy bandgap (3.4 eV), large free exciton binding energy (60 mV), high carrier mobility, high transparency at room temperature, and excellent photoelectric, piezoelectric, and thermoelectric properties [3,4]. The generation of hetero-structures is a basic requirement when developing structures for thin-film electronic and optoelectronic devices [3,4,5,6]. Few studies have reported the thermodynamic stability of un-doped MZO films deposited through RF magnetron sputtering [12,13]. We investigated the thermodynamic stability of Zr-doped MZO films through Hall measurements, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS)

Experiment

Results and Discussion

Conclusions