Post-growth annealing induced change of conductivity in As-doped ZnO grown by radio frequency magnetron sputtering

Abstract

Arsenic-doped ZnO films were fabricated by radio frequency magnetron sputtering method at a relatively low substrate temperature of 200 C. Post-growth annealing in air was carried out up to a temperature of 1000 C. The samples were characterized by Hall measurement, positron annihilation spectroscopy (PAS), secondary ion mass spectroscopy (SIMS), and cathodoluminescence (CL). The as-grown sample was of n-type and it converted to p-type material after the 400 C annealing. The resulting hole concentration was found to increase with annealing temperature and reached a maximum of 6 Â 10 17 cm À3 at the annealing temperature of 600 C. The origin of the p-type conductivity was consistent with the As Zn (V Zn) 2 shallow acceptor model. Further increasing the annealing temperature would decrease the hole concentration of the samples finally converted the sample back to n-type. With evidence, it was suggested that the removal of the p-type conductivity was due to the dissociation of the As Zn (V Zn) 2 acceptor and the creation of the deep level defect giving rise to the green luminescence. V

Thermal evolution of defects in undoped zinc oxide grown by pulsed laser deposition

“…Experimental defect study of ZnO has been performed using a variety of spectroscopic techniques like positron annihilation spectroscopy (PAS), [8][9][10][11][12][13][14][15] photoluminescence (PL), [16][17][18][19][20][21] and Raman spectroscopy (RS). [22][23][24][25][26] PAS is selectively sensitive to V Zn related defects.…”

“…8-10) and V Zn -hydrogen complexes 12 have been identified in n-type ZnO. PAS has also been used to study the different Znvacancy related phenomena like the thermal induced formation and the dissociation of the shallow acceptor in As-doped ZnO, 13,14 the residual donor responsible for the n-type conductivity in undoped ZnO, 15 etc. Broad defect emission bands with different wavelengths are frequently observed in ZnO materials.…”

Sb-related defects in Sb-doped ZnO thin film grown by pulsed laser deposition

“…To carry out the simulation, the following values were taken, namely, T po ¼ 837 K, e 1 ¼ 3:72 e vac and e 0 ¼ 8:12 e vac , c 1 ¼ 1:4 Â 10 11 Nm À2 , E 1 ¼ 3.8 eV, and m * ¼ 0.32m 0 (see references in Ref. 19). The film thickness was taken to be d ¼ 300 nm.…”

“…16 There were also experimental studies reporting the fabrication of p-type ZnO using these dopants (for example, Refs. [17][18][19][20][21].…”

Photoluminescence study of p-type vs. n-type Ag-doped ZnO films

“…It is known that structural, electrical, and optical properties of ZnO films are strongly influenced by deposition parameters, post treatment, and dopant elements. [11][12][13][14][15][16][17][18][19][20][21][22][23] Understanding the doping nature of impurities through investigation of microstructural and optical properties of ZnO is important for overcoming the bottleneck in realizing ZnO-based devices.…”