Oxygen-Doped Zinc Nitride as a High-Mobility Nitride-Based Semiconductor

Abstract

While many types of transparent conducting oxides (TCOs) have been developed, nitride-based transparent conductors remain rare. We examined the properties of zinc nitride doped with oxygen (Zn 3 N 2−x O x ) as a potential nitridebased transparent conductor. Electron density on the order of 10 20 cm −3 was achieved by heavy oxygen doping. A minimal resistivity (ρ) of 6.2 × 10 −4 Ω cm, comparable to those of TCOs, was observed for x = 0.19. Notably, the Zn 3 N 1.81 O 0.19 films had high electron mobility of 85 cm 2 V −1 s −1 , 2−3 times larger than the values for TCOs. Detailed analyses of mobility revealed that the electron transport was governed by ionized impurity scattering, and the dominant scattering center was substitutional oxygen. The contributions of additional scattering mechanisms were relatively minor. These findings explain the high observed mobility in Zn 3 N 2−x O x films. Contrary to our expectations, visible transmittance of Zn 3 N 2−x O x films was below 40%. X-ray photoelectron spectrometry suggested the existence of self-interstitial nitrogen (N I ) in Zn 3 N 2−x O x films. Low transmittance was attributable to optical absorption by electron transitions between the in-gap state originated from N I bonded to lattice nitrogen (N N ) and the band states. These results suggest that, when the formation of N N −N I bond is suppressed, Zn 3 N 2−x O x can be a high-mobility transparent conductor.

Carrier-Induced Band-Gap Variation and Point Defects in Zn3N2 from First Principles

“…One of the attractive nitrides is Zn 3 N 2 [13], whose biggest advantage is its high electron mobility, which exceeds 100 cm 2 V −1 s −1 [14][15][16][17] (the record is 395 cm 2 V −1 s −1 [15]). There have been reports suggesting the use of Zn 3 N 2 as transparent conductors [18], channel layers for optoelectronic devices [19], negative electrodes in Li-ion batteries [20], and precursor films for p-type doped ZnO [21]. Thus far, Zn 3 N 2 samples have been synthesized using various techniques, such as pulsed-laser deposition [22,23], molecular beam epitaxy [15,16,24], chemical vapor deposition [16,25], electrochemical processes [26], sputtering [17,[27][28][29][30], and ammonolysis reactions [31][32][33].…”

“…Besides, most Zn 3 N 2 samples have been found to be unintentionally n type with a carrier concentration of 10 18 -10 20 cm −3 . It is widely accepted that nitrogen vacancies and/or oxygen substitutions at nitrogen sites are responsible for the generation of such high carrier electrons [16,18,19,27,30,36]. However, there is still no clear theoretical support; researchers have investigated native defects [43], oxygen impurities [44], and copper, silver, and gold dopants [45] in Zn 3 N 2 in the neutral charge state using first-principles calculations.…”

Amorphous ZnOxNy thin films with high electron Hall mobility exceeding 200 cm2 V−1 s−1

“…This value is very different from those of ZnO and Zn 3 N 2 , indicating that the film consisted of a single-phase ZnO x N y , not a mixture of ZnO and Zn 3 N 2 . Although Zn 3 N 2 thin films containing interstitial nitrogen may show a similar optical gap, 19,20 this possibility can be eliminated from the results of XRD and Hall measurements, as described below. Figure 3 shows h-2h XRD patterns of the ZnO x N y thin films fabricated with various I ECR .…”

Low Working‐Temperature Acetone Vapor Sensor Based on Zinc Nitride and Oxide Hybrid Composites

“…[ 9 ] Zinc nitride (Zn 3 N 2 ) is an n-type group-II nitride semiconductor, having anti-bixbyite structure. [ 10 ] In addition, previous studies reported that the electron carrier concentration of Zn 3 N 2 is up to ≈1020 cm −3 and the electron mobilities could reach approximately 100 cm 2 V −1 s −1 . [ 11 ] Thus, by introducing Zn 3 N 2 into ZnO, the electron mobility is promoted, resulting in promising enhanced gas-sensing properties of the composite DOI: 10.1002/smll.201600422 Transition-metal nitride and oxide composites are a signifi cant class of emerging materials that have attracted great interest for their potential in combining the advantages of nitrides and oxides.…”