Improved p-type conductivity and acceptor states in N-doped ZnO thin films

Abstract

N-doped, p-type ZnO (ZnO : N) thin films were prepared by magnetron sputtering using NO as the N-doping source. The introduction of Ar in the growth ambient could evidently improve the p-type conductivity and crystal quality of the ZnO : N films, with the lowest room-temperature resistivity of 3.51 Ω cm obtained at an optimal Ar partial pressure of 30%. The p-type ZnO : N films have high optical quality, as suggested by temperature-dependent photoluminescence spectra. The NO substitution acceptor state with an energy level of 180 meV was identified from the free-to-neutral-acceptor (e, A 0) transition. The NO-acceptor bound-exciton binding energy was derived to be 17 meV from the neutral-acceptor-bound-exciton and free exciton emissions. The Haynes factor was about 0.094 for the NO acceptor in ZnO. Besides the NO acceptor, a zinc vacancy (VZn) acceptor state with an energy level of 255 meV was also identified in ZnO : N from the (e, A 0) transition, which might also contribute to the observed p-type conductivity.

High-efficiency micro-energy generation based on free-carrier-modulated ZnO:N piezoelectric thin films

“…Among the group V elements, the ionic size of N is most closely comparable to that of oxygen (O) in terms of radius (r N 3À ¼ 1:68 Å , and r O 2À ¼ 1:38 Å ), and helps to create acceptors (e.g., N substitutes for O sites in the ZnO lattice [N O ]); these acceptors compensated considerably for native donors in ZnO (e.g., Zn i , V O , or H). 8,9,[14][15][16] In this study, we intended to take full advantage of this N-compensatory doping, 26 which is expected to modulate the inherently n-typebiased ZnO conductivity more effectively and make it a more electrically resistive n-type material.…”

Impact of N5+ion implantation on optical and electrical properties of polycrystalline ZnO film

“…Decrease in mobility with fluence may be described by the potential barrier model (37), according to which the defects in the implanted ZnO films occurred at grain boundaries act as trapping centres for the carriers. These trapped electrons set up a negative charge and produce a space charge region in the grains.…”

Post-annealing influence on electrical properties and photoluminescence of B–N codoping ZnO thin films

“…The difference in the electrical properties between the two p-type ZnO:(B,N) is attributed to the difference in acceptor defect, that is, one is N O and another is V Zn. Some experimental studies results indicate that the energy level of V zn is about 0.3 eV above the valence band edge [27,28], While N O acceptor levels are in the range of 120-200 meV above the valence band edge, such as 165740 [29], 170-200 [30], 180 meV [28]. Since N O level is smaller than V Zn level, N O acceptor is activated more easier than V Zn , leading to that the ZnO:(B,N) annealed in vacuum has more hole concentration than the ZnO:(B,N) annealed in oxygen ambient.…”