Effects of annealing in N2 ambient on traps and persistent conduction in hydrothermally grown ZnO

Abstract

Thermally stimulated current ͑TSC͒ spectroscopy and temperature-dependent dark current ͑DC͒ measurements have been applied to study traps and photoinduced persistent surface conduction in two hydrothermally grown bulk ZnO samples, as-grown, and annealed at 600°C in N 2 ambient for 30 min, respectively. The as-grown sample had a room-temperature ͑RT͒ resistivity of 1.6 ϫ 10 3 ⍀ cm, mobility of 2.1ϫ 10 2 cm 2 / V s, and carrier concentration of 1.8ϫ 10 13 cm −3 , while the annealed sample was highly resistive, with RT resistivity of 3.6ϫ 10 6 ⍀ cm, mobility of 4.4 cm 2 / V s, and carrier concentration of 3.9ϫ 10 11 cm −3 . The as-grown sample showed strong conduction at low temperatures, which has been shown to be due to near-surface carriers in other studies. The annealed sample did not demonstrate this phenomenon. The dominant trap in the as-grown sample had an activation energy of 0.16 eV, was strongest near the surface, and is possibly related to V Zn . In the annealed sample, however, the dominant trap had an activation energy of 0.22 eV, was of bulk nature, and is tentatively assigned to Li Zn . After several routine TSC measurements, the DC for the as-grown sample increased by more than one order of magnitude at low temperatures ͑T Ͻ 180 K͒, while for the annealed sample, the DC increased by a factor of 2 at high temperatures ͑T Ͼ 200 K͒. These effects are generated by the TSC trap-filling illumination and can persist for many days under vacuum. At RT, the DC in the annealed sample returns to its equilibrium state if the sample is vented to air.

Low temperature thermally stimulated current measurements in N-implanted TlGaSeS layered single crystals

“…In the case of electronic devices, defects introduce scattering centers lowering carrier mobility, hence hindering high-frequency operation. Among the several experimental methods for determining the properties of trap centers in semiconductors, TSC measurements are relatively easy to perform and provide detailed information on trap states [12][13][14][15][16][17][18][19]. In TSC experiments, traps are filled by band-to-band excitation of carriers at low temperatures using a suitable light source.…”

Trap and recombination centers study in sprayed Cu2ZnSnS4 thin films

“…Among the several experimental methods for determining state properties in semiconductors, thermally stimulated current (TSC) measurements are relatively easy to perform and provide detailed information on trap and/or recombination states. [5][6][7][8][9][10][11][12] The TSC is one of the most effective tools for studying the defects behavior and their evolution upon different growth and post-thermal and chemical treatments. The TSC is known to be a very sensitive technique for studying point-defect and traps in semiconductors.…”

Computational modeling of isothermal decay curves of trapping centers in TlGaSeS layered single crystals

“…Thus, it is very useful to get detailed information on energetic and kinetic parameters of trapping centers (hole traps in the present paper) in semiconductor in order to obtain high quality devices. Among the several experimental methods for determining the properties of trap centers in semiconductors, thermally stimulated current (TSC) measurements are relatively easy to perform and provide detailed information on trap states [11][12][13][14][15][16][17][18][19].…”