The Effects of Zr Doping on the Optical, Electrical and Microstructural Properties of Thin ZnO Films Deposited by Atomic Layer Deposition

Abstract

Transparent conducting oxides (TCOs), with high optical transparency (≥85%) and low electrical resistivity (10−4 Ω·cm) are used in a wide variety of commercial devices. There is growing interest in replacing conventional TCOs such as indium tin oxide with lower cost, earth abundant materials. In the current study, we dope Zr into thin ZnO films grown by atomic layer deposition (ALD) to target properties of an efficient TCO. The effects of doping (0–10 at.% Zr) were investigated for ~100 nm thick films and the effect of thickness on the properties was investigated for 50–250 nm thick films. The addition of Zr4+ ions acting as electron donors showed reduced resistivity (1.44 × 10−3 Ω·cm), increased carrier density (3.81 × 1020 cm−3), and increased optical gap (3.5 eV) with 4.8 at.% doping. The increase of film thickness to 250 nm reduced the electron carrier/photon scattering leading to a further reduction of resistivity to 7.5 × 10−4 Ω·cm and an average optical transparency in the visible/near infrared (IR) range up to 91%. The improved n-type properties of ZnO: Zr films are promising for TCO applications after reaching the targets for high carrier density (>1020 cm−3), low resistivity in the order of 10−4 Ω·cm and high optical transparency (≥85%).

Effect of Zr doping on the electrical and optical properties of ZnO

“…The results indicate that while the Zr-doping amount is within the range of 0.02083-0.04167, the higher the doping amount is, the higher the electron concentration of the doping system is. The calculation results and the experiment results [33] are consistent.…”

“…Therefore, the higher the Zr-doping amount is, the higher the conductivity is. The calculation results and the experiment results [33] are consistent. Under low-temperature environmental conditions, new-type Zr-doped ZnO is designed and prepared to obtain new semiconductor materials, which provides theoretical guidance for thermoelectric power generation function materials at low temperature end.…”

“…It can be seen from According to the formula of average electron effective mass: Table 2. It can be seen from Table 2 that the average electron effective of pure ZnO is consistent with Reference [33], and the higher Zr-doping amount is, the bigger the average electron effective of doping system is. The results indicate that while the Zr-doping amount is within the range of 0.02083-0.04167, the higher the doping amount is, the higher the electron concentration of the doping system is.…”

“…40eV, α=1×10 -3 eV/K, β=900K [33]. According to the Formula (6), temperature has some influence on changes in the band gap of doping system, the higher the temperature is, the narrower the band gap is.…”

Electric Conduction Mechanisms Study within Zr Doped Mn3O4 Hausmannite Thin Films through an Oxidation Process in Air

“…This indicates that Zr Zn defect forms easier and its concentration may be the highest in doped films (Wang et al, 2008). However, when the doping reaches 20 at.%, the resistance increases again which could be explained by the fact that Zr element cannot incorporate into Mn 3 O 4 matrix and it remains as an impurity in various forms of ZrO x or ZrO 2 , which lead (Herodotou et al, 2015;Lv et al, 2008;Paul et al, 2003;Wang et al, 2014). These results are consistent with those found elsewhere (Said et al, 2017) As a matter of fact, the dielectric relaxation time is closely related to the electrical conductivity.…”