Nitrogen function of aluminum-nitride codoped ZnO films deposited using cosputter system

Abstract

AlN codoped ZnO films were deposited on sapphire substrates at low temperature using a cosputter system under various N2/(N2 + Ar) flow ratios. To investigate the nitrogen function, the ratio of nitrogen ambient was varied during cosputtering. AlN codoped ZnO films with various crystallographic structures and bonding configurations were measured. With an adequate nitrogen atmosphere deposition condition and postannealing temperature at 450 °C, the p-type conductive behaviors of AlN codoped ZnO films were achieved due to the formation of Zn–N bonds. According to the low-temperature photoluminescence spectra, the binding energy (EA) of 0.16 eV for N acceptors can be calculated. Using time-resolved photoluminescence measurement, the carrier lifetime in AlN codoped ZnO films increases due to the reduction of oxygen vacancies caused by the occupation of adequate nitrogen atoms.

Fabrication Methods and Luminescent Properties of ZnO Materials for Light-Emitting Diodes

“…TThe GL bands were often found in observed PL spectra of samples prepared in our lab and they usually were attributed to oxygen vacancy defects. For example, a green-band emission was observed both for the undoped ZnO film and the p-type AlN codoped ZnO films [ 58 ], and the intensities were smaller for the latter, which implies that less oxygen vacancies existed in them. However, in a work on ZnO-on-GaN heterostructures grown using the vapor cooling condensation system [ 39 ], compared to undoped ZnO, a remarkable broad green emission band in ZnO:In films was observed, and it was considered to be induced by the oxygen vacancies.…”

“…In order to improve the quality of p -type ZnO codoped with AlN and study the function of nitrogen in these films in more detail, we [ 120 ] prepared a series of AlN codoped ZnO films using the same radio frequency (rf) magnetron cosputtering system, but under various N 2 /(N 2 + Ar) flow ratios and with lower rf power. The rf powers of AlN and ZnO were fixed at 25 and 100 W, respectively, and the N 2 /(N 2 + Ar) flow ratios of 0%, 4%, 8%, and 12% were used with the total flow rate kept at 50 sccm Then the prepared samples were post-annealed at 400, 450, and 500 °C for 10 min in a N 2 ambient to activate the doping impurities.…”

Homostructured ZnO-based metal-oxide-semiconductor field-effect transistors deposited at low temperature by vapor cooling condensation system

“…Among various devices, the one of homojunction structures is of specific interest due to the better interfacial quality between different layers. However, it is very difficult to obtain p-ZnO and intrinsic ZnO (i-ZnO) films, because the ZnO semiconductor naturally exhibits n-type conduction behaviors owing to the low formation energy of shallow donors induced by oxygen vacancies or zinc interstitials [7,8]. Consequently, n-ZnO films were mostly used in various devices by forming heterojunction with other p-type semiconductors [9][10][11].…”

Investigation of Single n-ZnO/i-ZnO/p-GaN-Heterostructed Nanorod Ultraviolet Photodetectors

“…In general, with proper doping impurities chosen, high quality n-type ZnO (n-ZnO)-based semiconductors could easily be obtained. However, since ZnO semiconductor is naturally an n-type semiconductor owing to the compensation effect of shallow donors induced by zinc interstitials or oxygen vacancies [11], [12], it becomes rather difficult to obtain high quality p-type ZnO (p-ZnO) and intrinsic ZnO (i-ZnO) films and nanorods with a reproducible fashion. In the past decades, with the significant progress being achieved in epitaxial growth and ohmic/Schottky contacts [13]- [15], GaN-based semiconductors have already been widely employed in the applications of gas sensors [16], electronic devices [17], and optoelectronics devices [18].…”