Helicon‐wave‐excited plasma sputtering deposition of Ga‐doped ZnO transparent conducting films

Abstract

Sputtering deposition of Ga-doped ZnO (ZnO : Ga) thin films was carried out using the helicon-waveexcited plasma sputtering (HWPS) method. The films sputtered above 150 °C had a preferential {0001} orientation. According to the surface-damage-free nature, the films having featureless surface morphology exhibited an optical transmittance greater than 80% in the visible spectral wavelengths. However, because the deposition temperature was limited to 250 °C, the electron mobility was limited to as low as 2-3 cm 2 /V s due to the small grain size (∼ 25 nm). The results indicate that ZnO : Ga films deposited by HWPS can be used in the transparent conducting oxide layer, provided that higher electron mobility is achieved.

Investigation of Ga Substitution in ZnO Powder and Opto-Electronic Properties

“…Ga-doped ZnO compounds can be used as Al-doped ZnO powder (most developed) as transparent conductive oxides (TCOs), which are useful as transparent electrodes (optoelectronic devices), [1][2][3][4][5][6][7][8][9][10][11][12] or as thermal insulator films in smart windows (low emissive windows). [1][2][3] Indeed, ZnO is a large gap semiconductor with native n-type defects which accepts efficient doping by n-type donors as M 3þ metallic elements or halogens as F -.…”

Fabrication of a n ‐type ZnO/p ‐type Cu–Al–O heterojunction diode by sputtering deposition methods

“…Sputtering deposition using HWP is called 'helicon-wave-excited plasma sputtering' (HWPS). Thus far, the deposition of low-resistivity and high-transparency ZnO:Al [12] and ZnO:Ga [13,14] TCOs on soda-lime glass, epitaxial growth of ZnO on sapphire substrates [15,16], and deposition of a SiO 2 /ZrO 2 multilayer dielectric distributed Bragg reflectors (DBR) [17] have been demonstrated by the HWPS method. This article demonstrates HWPS deposition of CuAlO 2 thin CuAlO 2 polycrystalline films were deposited by the heliconwave-excited plasma sputtering (HWPS) method at 700 °C.…”

“…Details of the HWPS system have been provided in previous reports [12][13][14][15][16]. The substrate was located nearly parallel to a 2-inch-diameter 2CuO-Al 2 O 3 sintered target with grounding.…”

“…The growth temperature was maintained at 500 °C. After depositing p-type Cu-Al-O film, ZnO:Ga/ZnO n-type TCO layers were deposited by HWPS, in order to prevent the surface from re-sputtering and/or damage [12][13][14][15][16][17]. The thicknesses of the ZnO and ZnO:Ga layers were approximately 150 and 200 nm, respectively.…”

Fabrication of Zn‐doped Cu(In,Ga)Se2 thin film solar cells prepared by Zn diffusion from the gas phase using dimethylzinc

“…The ZnO:Ga/MgZnO window layer was deposited by the helicon-wave-excited plasma sputtering (HWPS) method to prevent the surface from re-sputtering and plasma damage [17,18]. Conventional CIGS solar cell structures without Zn-diffusion or with a CBD-CdS buffer layer were also prepared as reference samples.…”