Deep acceptor states in ZnO single crystals

Electron and hole traps in N-doped ZnO were investigated using a structure of n + -ZnO:Al/ i-ZnO/ ZnO:N grown on a p-Si substrate by metalorganic chemical vapor deposition ͑for growth of the ZnO:N layer͒ and sputtering deposition ͑for growth of the i-ZnO and n + -ZnO:Al layers͒. Current-voltage and capacitance-voltage characteristics measured at temperatures from 200 to 400 K show that the structure is an abrupt n + − p diode with very low leakage currents. By using deep level transient spectroscopy, two hole traps, H3 ͑0.35 eV͒ and H4 ͑0.48 eV͒, are found in the p-Si substrate, while one electron trap E3 ͑0.29 eV͒ and one hole trap H5 ͑0.9 eV͒ are observed in the thin ZnO:N layer. Similarities to traps reported in the literature are discussed.

Section: Resultsmentioning

confidence: 55%

“…A recent DLTS study has revealed deep acceptor states ͑hole traps͒ in ZnO single crystals using a novel p − n junction formed by N + implantation. 8 In that study, an N + -implanted p-ZnO layer was employed for injecting holes. Here, we present a DLTS investigation of a ZnO:N thin film incorporated into a p − n junction diode.…”

Section: Introductionmentioning

confidence: 99%

Electron and hole traps in N-doped ZnO grown on p-type Si by metalorganic chemical vapor deposition

Fang

Claflin

Kerr

et al. 2007

“…However, the electron irradiation introduces a new trap with an activation energy of 0.15 eV, and other traps of energy 0.30 and 0.80 eV, respectively. From a comparison of these results with positron annihilation experiments and density functional theory, we conclude that the 0.15-eV trap may be related to V Zn 4,5 Both materials contained two prominent defects: E1 at E C − 0.12 eV and E3 at E C − 0.29 eV. In VP ZnO, E1 is the primary defect, while in MLT ZnO, E3 dominates.…”

Section: G C Farlowmentioning

confidence: 84%

Electron irradiation induced deep centers in hydrothermally grown ZnO

Fang

Claflin

Look

et al. 2007

An n-type hydrothermally grown ZnO sample becomes semi-insulating (ρ~108 Ω cm) after 1-MeV electron-irradiation. Deep traps produced by the irradiation were studied by thermally stimulated current spectroscopy. The dominant trap in the as-grown sample has an activation energy of 0.24 eV and is possibly related to LiZn acceptors. However, the electron irradiation introduces a new trap with an activation energy of 0.15 eV, and other traps of energy 0.30 and 0.80 eV, respectively. From a comparison of these results with positron annihilation experiments and density functional theory, we conclude that the 0.15-eV trap may be related to VZn.

“…techniques. [14][15][16][17][18][24][25][26][27] However, the microscopic origins of this defect are not clear as yet. Annealing ZnO samples in different ambient increases the intensity of the DLTS peak for the E3 defect (Figure 3(a)), with the highest intensity being observed for the Ar þ O 2 annealed samples.…”

Section: Emission Properties Of E3mentioning

confidence: 99%

A study of the T2 defect and the emission properties of the E3 deep level in annealed melt grown ZnO single crystals

Mtangi

Schmidt

Auret

et al. 2013

We report on the space charge spectroscopy studies performed on thermally treated melt-grown single crystal ZnO. The samples were annealed in different ambients at 700 C and also in oxygen ambient at different temperatures. A shallow donor with a thermal activation enthalpy of 27 meV was observed in the as-received samples by capacitance-temperature, CT scans. After annealing the samples, an increase in the shallow donor concentrations was observed. For the annealed samples, E27 could not be detected and a new shallow donor with a thermal activation enthalpy of 35 meV was detected. For samples annealed above 650 C, an increase in acceptor concentration was observed which affected the low temperature capacitance. Deep level transient spectroscopy revealed the presence of five deep level defects, E1, E2, E3, E4, and E5 in the as-received samples. Annealing of the samples at 650 C removes the E4 and E5 deep level defects, while E2 also anneals-out at temperatures above 800 C. After annealing at 700 C, the T2 deep level defect was observed in all other ambient conditions except in Ar. The emission properties of the E3 deep level defect are observed to change with increase in annealing temperature beyond 800 C. For samples annealed beyond 800 C, a decrease in activation enthalpy with increase in annealing temperature has been observed which suggests an enhanced thermal ionization rate of E3 with annealing. V C 2013 American Institute of Physics. [http://dx