Energetically deep defect centers in vapor-phase grown zinc oxide

Frank, Thomas; Pensl, Gerhard; Tena‐Zaera, Ramón; Zúñiga‐Pérez, Jesús; Martı́nez-Tomás, C.; Muñoz‐Sanjosé, V.; Ohshima, Takeshi; Itoh, Hisayoshi; Hofmann, Detlev M.; Pfisterer, D.; Sann, Joachim; Meyer, B. K.

doi:10.1007/s00339-007-3963-3

Cited by 48 publications

(59 citation statements)

References 7 publications

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“…The attribution is probably based on activation energy of the level which seems not to be plausible in accordance with Vincent et al 15 who suggested that it was necessary to become vigilant before interpreting the data attained for a carrier trap using capacitance transient measurement of diodes having N D greater than 10 15 cm −3 , as practically evidenced in Fig. 4 ͑the data include our results and those reported by other research groups 12,22,25 ͒. The information from the literature indicates that the reduction in thermal emission energy of a defect level is linked with the electric field enhanced emission.…”

Section: -3supporting

confidence: 75%

“…2 observed intrinsic donorlike defects in ZnO having an activation energy in the range of 0.30 to 0.37 eV, Frank et al 12 demonstrated a Zn-related defect level with an ionization energy of 0.31 eV, and Auret et al 13 reported a similar level at an energy of 0.29 eV and attributed to an oxygen vacancy. In short, the activation energy of the defect exhibits upto 40% variation, and the nature of the defect level oscillates between the Zninterstitial and the oxygen vacancy that is why no acceptable identification of the level is found.…”

Section: Introductionmentioning

confidence: 95%

“…Hence, the level E 1 is identified as a charged impurity. Furthermore, the majority of the research groups have reported Zn-related electron traps ͑interstitials and antisites͒ in intrinsically n-type ZnO material exhibiting relatively shallower energy spectrum ͑0.22-0.32 eV͒, 11,12,17,22,25 we therefore, attribute the foresaid charged impurity with Zn. This argument is consistent with the theoretical calculations revealing that Zninterstitials are shallower than O-related defects ͑interstitials and antisites͒ in ZnO.…”

Section: -3mentioning

confidence: 99%

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Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices

Noor

Klason

Faraz

et al. 2010

Journal of Applied Physics

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Various well-known research groups have reported points defects in bulk zinc oxide ͑ZnO͒ ͓N D ͑intrinsic͒: 10 14 -10 17 cm −3 ͔ naming oxygen vacancy, zinc interstitial, and/or zinc antisite having activation energy in the range of 0.32-0.22 eV below conduction band. The attribution is probably based on activation energy of the level which seems not to be plausible in accordance with Vincent et al., ͓J. Appl. Phys. 50, 5484 ͑1979͔͒ who suggested that it was necessary to become vigilant before interpreting the data attained for a carrier trap using capacitance transient measurement of diodes having N D greater than 10 15 cm −3 . Accordingly the influence of background free-carrier concentration, N D induced field on the emission rate signatures of an electron point defect in ZnO Schottky devices has been investigated by means of deep level transient spectroscopy. A number of theoretical models were tried to correlate with the experimental data to ascertain the mechanism. Consequently Poole-Frenkel model based on Coulomb potential was found consistent. Based on these investigations the electron trap was attributed to Zn-related charged impurity. Qualitative measurements like current-voltage and capacitance-voltage measurements were also performed to support the results.

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Section: -3supporting

confidence: 75%

Section: Introductionmentioning

confidence: 95%

Section: -3mentioning

confidence: 99%

See 1 more Smart Citation

Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices

Noor

Klason

Faraz

et al. 2010

Journal of Applied Physics

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“…Similar to SnO 2 , computational studies tend to indicate that the oxygen vacancy is deep, with the (2+/0) transition occurring at about 1 eV below the CBM [46][47][48][49][50][51][52][53]. There are a number of signals detected using deep level transient spectroscopy that have been attributed to oxygen vacancies [93][94][95], but the consistency of these attributions with results from computational studies is a matter of debate.…”

Section: Introductionmentioning

confidence: 95%

Deep vs shallow nature of oxygen vacancies and consequentn-type carrier concentrations in transparent conducting oxides

Buckeridge

Catlow

Farrow

et al. 2018

Phys. Rev. Materials

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The source of n-type conductivity in undoped transparent conducting oxides has been a topic of debate for several decades. The point defect of most interest in this respect is the oxygen vacancy, but there are many conflicting reports on the shallow versus deep nature of its related electronic states. Here, using a hybrid quantum mechanical/molecular mechanical embedded cluster approach, we have computed formation and ionization energies of oxygen vacancies in three representative transparent conducting oxides: In 2 O 3 , SnO 2 , and ZnO. We find that, in all three systems, oxygen vacancies form well-localized, compact donors. We demonstrate, however, that such compactness does not preclude the possibility of these states being shallow in nature, by considering the energetic balance between the vacancy binding electrons that are in localized orbitals or in effective-mass-like diffuse orbitals. Our results show that, thermodynamically, oxygen vacancies in bulk In 2 O 3 introduce states above the conduction band minimum that contribute significantly to the observed conductivity properties of undoped samples. For ZnO and SnO 2 , the states are deep, and our calculated ionization energies agree well with thermochemical and optical experiments. Our computed equilibrium defect and carrier concentrations, however, demonstrate that these deep states may nevertheless lead to significant intrinsic n-type conductivity under reducing conditions at elevated temperatures. Our study indicates the importance of oxygen vacancies in relation to intrinsic carrier concentrations not only in In 2 O 3 , but also in SnO 2 and ZnO.

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“…It has been suggested that E4 is the singly negative charge state of the oxygen vacancy [23], although the identification is rather tentative.…”

Section: A Dlts and Tas Measurementsmentioning

confidence: 99%

Lithium and electrical properties of ZnO

Vines

Monakhov

Schifano

et al. 2010

Journal of Applied Physics

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Energetically deep defect centers in vapor-phase grown zinc oxide

Cited by 48 publications

References 7 publications

Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices

Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices

Deep vs shallow nature of oxygen vacancies and consequentn-type carrier concentrations in transparent conducting oxides

Lithium and electrical properties of ZnO

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