Electrical characteristics of Au and Ag Schottky contacts on n-ZnO

Polyakov, A. Y.; Smirnov, N. B.; Кожухова, Е. А.; Vdovin, V. I.; Ip, K.; Heo, Young‐Woo; Norton, D. P.; Pearton, S. J.

doi:10.1063/1.1604173

Cited by 186 publications

(102 citation statements)

References 26 publications

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“…These spectra were obtained in the 30-330-K temperature range, at a reverse bias of -2.0 V, filling pulse width of 2.0 ms, and filling pulse of 0.3 V. The annealed samples and the un-annealed samples show three prominent defects, E1, E2, and E3, that have been observed in ZnO and reported before. [16][17][18][19] The 300 C Ar annealing of the ZnO samples introduces a new peak E4 300 C , as has also been reported by Ref. 20.…”

Section: Resultssupporting

confidence: 59%

Effects of high temperature annealing on single crystal ZnO and ZnO devices

Mtangi

Auret

Diale

et al. 2012

Journal of Applied Physics

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AlN thin film transducers for high temperature non-destructive testing applications J. Appl. Phys. 111, 074510 (2012) Fast programming metal-gate Si quantum dot nonvolatile memory using green nanosecond laser spike annealing Appl. Phys. Lett. 100, 143501 (2012) Al2O3/InAs metal-oxide-semiconductor capacitors on (100) and (111)B substrates Appl. Phys. Lett. 100, 132905 (2012) Sub-diffraction-limit semiconductor resonators operating on the fundamental magnetic resonance Appl. Phys. Lett. 100, 131113 (2012) Additional information on J. Appl. Phys. We have systematically investigated the effects of high-temperature annealing on ZnO and ZnO devices using current voltage, deep level transient spectroscopy (DLTS) and Laplace DLTS measurements. Current-voltage measurements reveal the decrease in the quality of devices fabricated on the annealed samples, with the high-temperature annealed samples yielding devices with low barrier heights and high reverse currents. DLTS results indicate the presence of three prominent defects in the as-received samples. Annealing the ZnO samples at 300 C, 500 C, and 600 C in Ar results in an increase in reverse leakage current of the Schottky contacts and an introduction of a new broad peak. After 700 C annealing, the broad peak is no longer present, but a new defect with an activation enthalpy of 0.18 eV is observed. Further annealing of the samples in oxygen after Ar annealing causes an increase in intensity of the broad peak. High-resolution Laplace DLTS has been successfully employed to resolve the closely spaced energy levels. V C 2012 American Institute of Physics. [http://dx

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Section: Resultssupporting

confidence: 59%

Effects of high temperature annealing on single crystal ZnO and ZnO devices

Mtangi

Auret

Diale

et al. 2012

Journal of Applied Physics

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“…1 also contributes to the limitation in the accurate determination of E1. The E3 defect with activation energy (0.32 6 0.01) eV below the conduction band is possibly the same defect that was observed by Polyakov et al 21 on samples obtained from Eagle-Pitcher, Grundmann et al 6 in pulsed laser deposited ZnO, and Auret et al 19 in melt grown ZnO. Its identity has been attributed to intrinsic defects, either interstitial zinc or the oxygen vacancy V o .…”

Section: Resultsmentioning

confidence: 50%

A comparative study of the electrical properties of Pd/ZnO Schottky contacts fabricated using electron beam deposition and resistive/thermal evaporation techniques

Mtangi

Auret

Rensburg

et al. 2011

Journal of Applied Physics

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A systematic investigation to check the quality of Pd Schottky contacts deposited on ZnO has been performed on electron beam (e-beam) deposited and resistively/thermally evaporated samples using current-voltage, IV, and conventional deep level transient spectroscopy (DLTS) measurements. Room temperature IV measurements reveal the dominance of pure thermionic emission on the resistively evaporated contacts, while the e-beam deposited contacts show the dominance of generation recombination at low voltages, <0.30 V, and the dominance of pure thermionic emission at high voltages, greater than 0.30 V. The resistively evaporated contacts have very low reverse currents of the order of 10 À10 A at a reverse voltage of 1.0 V whereas the e-beam deposited contacts have reverse currents of the order of 10 À6 A at 1.0 V. Average ideality factors have been determined as (1.43 6 0.01) and (1.66 6 0.02) for the resistively evaporated contacts and e-beam deposited contacts, respectively. The IV barrier heights have been calculated as (0.721 6 0.002) eV and (0.624 6 0.005) eV for the resistively evaporated and e-beam deposited contacts, respectively. Conventional DLTS measurements reveal the presence of three prominent defects in both the resistive and e-beam contacts. Two extra peaks with energy levels of 0.60 and 0.81 eV below the conduction band minimum have been observed in the e-beam deposited contacts. These have been explained as contributing to the generation recombination current that dominates at low voltages and high leakage currents. Based on the reverse current at 1.0 V, the degree of rectification, the dominant current transport mechanism and the observed defects, we conclude that the resistive evaporation technique yields better quality Schottky contacts for use in solar cells and ultraviolet detectors compared to the e-beam deposition technique. The 0.60 eV has been identified as possibly related to the unoccupied level for the doubly charged oxygen vacancy, V o 2þ .

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“…Polyakov et al [55] reported that annealing of Au SCs at ∼ 100 o C is already sufficient to cause surface reactions resulting in a near surface layer with reduced electron concentration and high density of deep defects. However, the thermal stability of Ag SCs seems to be higher and these contacts withstanding up to ∼ 100 o C without degrading significantly [60].…”

Section: The State Of the Artmentioning

confidence: 99%

“…However, despite the first SC to ZnO was reported by Mead [51] already in 1965, it is still challenging to realize stable and high quality SCs. For instance, the presence of a conductive surface layer due to group III ions [53], native defects both resident in the bulk and created by the metallization [54], processing [55], adsorbates [56,57], sample orientation [58,59] and presence of surface dipoles [60], can all affect the ZnO surface and the metal-semiconductor junction performance. Similar effects can account for the wide scatter, up to ∼ 2 eV in the ZnO work function (i.e.…”

Section: The State Of the Artmentioning

confidence: 99%

“…χ s + (E C − E F ), In addition, the SCs ideality factor (n) for the current-voltage characteristics are substantially higher than unity as will be discussed more in Chapter IV. SCs can be accomplished by using a simple pre-cleaning of the ZnO samples in organic solvents [62,55], but in many cases the rectifying behavior, or the improved rectification, involves some kind of more advanced surface pretreatment: in oxygen plasma [57,54], in hydrogen peroxide [63,64], or a (NH 4 ) 2 S x solution [65], etching of the surface using HCl [66], or a soak in concentrated H 3 PO 4 followed by a dip in HCl [37]. The use of metal oxides, like AgO, as a contact material seems also to represent a valid alternative; SCs with a high barrier, Φ b ∼ 1 eV, and low ideality factors, n ∼ 1.0 − 1.1, have been obtained in this case [67].…”

Section: The State Of the Artmentioning

confidence: 99%

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Electrical characteristics of palladium Schottky contacts to hydrogen peroxide treated hydrothermally grown ZnO

Schifano¹,

Monakhov²,

Großner³

et al. 2007

Applied Physics Letters

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The formation of Schottky barrier contacts to hydrogen peroxide treated ZnO has been investigated. Low resistivity hydrothermally grown single crystal ZnO wafers of n-type were used. Pd contacts deposited on organic solvent cleaned O face (0001¯) showed Ohmic behavior, while on the H2O2 treated O face up to nine orders of magnitude in rectification of the current was obtained for biases of −2 and +2V. Concurrently, the surface roughness increases from 1.0±0.5 up to 2.0±0.5nm due to the H2O2 treatment. A majority of the contacs deposited were stable or improved their performance by annealing in air at 200°C for 30min. However, the contacts both before and after the annealing exhibited ideality factors of at least ∼1.8 at +0.5V suggesting that the current transport cannot be described as purely thermionic. Finally, results of capacitance versus voltage and capacitance versus temperature measurements are discussed and show a dominant electron state at ∼0.32eV below the conduction band edge.

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Electrical characteristics of Au and Ag Schottky contacts on n-ZnO

Cited by 186 publications

References 26 publications

Effects of high temperature annealing on single crystal ZnO and ZnO devices

Effects of high temperature annealing on single crystal ZnO and ZnO devices

A comparative study of the electrical properties of Pd/ZnO Schottky contacts fabricated using electron beam deposition and resistive/thermal evaporation techniques

Electrical characteristics of palladium Schottky contacts to hydrogen peroxide treated hydrothermally grown ZnO

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