Characteristics of GZO Films Prepared by Using a rf MagnetronPlasma at Low Temperature

Dependence of Ga-doped ZnO thin film properties on different sputtering process parameters: Substrate temperature, sputtering pressure and bias voltage

“…In these conditions, the lack of oxygen in the films is relevant, and oxygen vacancies can be created [26]. On the other hand, at higher deposition pressures (above 0.665 Pa), the O/Zn ratio of the ZnO:Ga films starts to increase with increasing Ar pressure [11]. This suggests that in the present manuscript a very low pressure range is involved, in which the oxygen vacancies are further created with the increasing of argon pressure.…”

“…For the application of ZnO:Ga thin films as a transparent conductor electrodes in photovoltaic applications, the most important factors to take into account are the optical transmittance (which must be high) and electrical resistivity (which should be as low as possible) [11]. In the present paper, it is presented the study of the influence of different sputtering process parameters: substrate temperature, sputtering pressure and substrate bias voltage, on the electrical, optical and structural properties of ZnO:Ga thin films.…”

“…Park and coworkers [13] reported that the (002) diffraction angle of all the films slightly deviated to lower angles from that of the standard ZnO; they observed that the lattice strain decreased as the deposition temperature increased (and also the angle deviation was smaller), which means that substitution of Zn 2+ by Ga 3+ is enhanced upon higher deposition temperatures [13]. No other diffraction peaks from other compounds (such as Ga 2 O 3 ) were registered, indicating that the doped Ga atoms did not change the ZnO crystal structure, and Ga atoms replace Zn in the hexagonal lattice or are segregated to the non-crystalline region in grain boundary [8,11,21,22]. As expected, the full width at half maximum of the ZnO (002) diffraction peak decreases with increasing deposition temperature, indicating an improvement of the crystalline quality [13].…”

“…In fact, in agreement with the present study, this deterioration is also observed at lower deposition pressure; it seems that at very low deposition pressures the particles when arriving at the substrate surface do not have enough energy (and therefore have low mobility), resulting in more irregular crystalline lattice formation. In another study that involved the influence of different deposition pressures (from 0.133 to 1.463 Pa), W. C. Song and co-workers [11] observed that, at pressures between 0.665 and 1.463 Pa, the resistivity of the ZnO:Ga films increased with the increasing of Ar pressure. However, from 0.133 to 0.665 Pa (a similar pressure range to that being studied in this manuscript), the resistivity of the ZnO:Ga films decreased with increasing the Ar pressure, achieving a minimum of 1.5 × 10 − 3 Ω•cm at a sputtering pressure of 0.665 Pa, which is higher than that obtained in the present study.…”

“…However, from 0.133 to 0.665 Pa (a similar pressure range to that being studied in this manuscript), the resistivity of the ZnO:Ga films decreased with increasing the Ar pressure, achieving a minimum of 1.5 × 10 − 3 Ω•cm at a sputtering pressure of 0.665 Pa, which is higher than that obtained in the present study. Based on dispersive X-ray analyses, they observed that with increasing Ar pressure, the O/Zn ratio of the ZnO:Ga films becomes gradually lower at pressures below 0.665 Pa [11]. In these conditions, the lack of oxygen in the films is relevant, and oxygen vacancies can be created [26].…”