Characteristics of nitrogen-doped p-ZnO thin films and ZnO/ZnSe p–n heterojunctions grown on a ZnSe substrate

Abstract

We investigate p-type doping in ZnO prepared by the method of radical beam gettering epitaxy using NO gas as the oxygen source and nitrogen dopant. A narrow (0 0 2) peak is observed in the x-ray diffraction spectra, which indicates that the N-doped ZnO films are oriented along the c-axis. Secondary ion mass spectroscopy measurements demonstrate that N is incorporated into a ZnO film with a concentration of about 2.5 × 10 19 cm −3 . The hole concentration of the N-doped p-ZnO films was between 1.4 × 10 17 and 7.2 × 10 17 cm −3 , and the hole mobility was 0.9-1.2 cm 2 V −1 s −1 as demonstrated by Hall-effect measurements. The emission peak of 3.312 eV is observed in the photoluminescence spectra at 4.2 K of N-doped p-ZnO films, probably neutral acceptor bound excitons and the band of 3.24 eV, connected with a donor-acceptor pair recombination. The activation energy of the nitrogen acceptor was obtained by the temperature-dependent Hall-effect measurement, and is about 145 meV. The p-n heterojunctions ZnO/ZnSe were grown on the n-type ZnSe substrate, and have a turn-on voltage of about 3.5 V.

Nitrogen doped-ZnO/n-GaN heterojunctions

“…Also, the emission lines in this spectral region are typically attributed to native defects. 12 The peaks related to nitrogen doping at $3.31-3.315 eV (acceptor bound exciton), 12,14 and 3.24 eV donoracceptor pair (DAP) emission 14 could not be clearly resolved, although from the shape of the peak contributions in this spectral region cannot be excluded.…”

“…1,3,4 Among different possible acceptor dopants for ZnO, nitrogen has been regarded as one of the most suitable acceptors due to its similar atomic size and electronic structure to oxygen, 3 and hence, it has been extensively studied. [5][6][7][8][9][10][11][12][13][14][15][16] However, p-type conductivity in N:ZnO remains controversial. 3,4 Recent theoretical calculations indicated that nitrogen is a deep acceptor, 5 although hole binding energy derived from PL experiments on N:ZnO was comparable to that observed for Mg in GaN, 4 indicating that nitrogen is a shallow acceptor.…”

“…P-type conductivity in N:ZnO, grown by variety of methods and with different nitrogen sources, has been reported to date. [9][10][11][12][13][14][15][16] In addition, in spite of the concerns on the reproducibility and stability of p-type doping in ZnO, 1,4 stable p-type conductivity for five months of storage in air was reported for N:ZnO. 9 Consequently, nitrogen doping for the achievement of p-type ZnO has significant potential, provided that native and other compensating defects can be controlled to avoid compensation.…”

Thermal activation of nitrogen acceptors in ZnO thin films grown by MOCVD

“…This transition could be due to donor-acceptor pair (DAP) recombination, which involves the same acceptor as the (FA) transition at 3.314 eV. Transitions at ∼3.24 eV and ∼3.17 eV have been reported in ZnO doped with nitrogen [9,10]. Rogozin et al [9] reported a DAP emission at 3.24 eV in their p-type ZnO grown with NO.…”

Electrical Properties of Anisotype ZnO/ZnSe Heterojunctions

“…To overcome this drawback a number of technologies can be used (MBE, metal organic chemical vapor deposition (MOCVD), ion implantation), but all of them need complex and expensive facilities and a suppression of radiation defects by additional annealing. Recently, a new method has been proposed, which is the ZnO:N thin films deposition using the radical-beam generating epitaxy method for p-ZnO/ n-ZnSe anisotropic heterojuction formation [2]. In this work we report on the photothermal oxidation method applied to the mentioned heterojunction fabrication and the studies of its electric properties.…”