The optical signature of electron injection in p-(Al)GaN

Burdett, William; Lopatiuk, O.; Osinsky, A.; Pearton, S. J.; Chernyak, Leonid

doi:10.1016/j.spmi.2004.02.019

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…The experiments were carried out on commercially available (Tokyo Denpa (TD)) bulk ZnO substrates grown by hydrothermal technique. Secondary Ion Mass Spectroscopy (SIMS) measurements performed on these substrates revealed the presence of lithium (Li) in the crystal on the level of ~ 4x10 16 cm -3 (Li is often added to ZnO to increase the resistivity of initially n-type samples) (12). Room temperature Hall measurements showed the samples to be a weak n-type with an electron concentration of ~ 10 14 cm -3 and mobility of ~ 150 cm 2 /Vs.…”

Section: Electron Injection In Bulk Zno Substratesmentioning

confidence: 99%

“…As L is proportional to the square root of lifetime and depends linearly on t (14,15,16), the inverse CL intensity, 1/I, which is also proportional to   τ (larger τ ensures longer nonequilibrium minority carrier stay in the band, and, as a result, lower rate of radiative recombination), should depend on the duration of electron injection quadratically. This is, indeed, observed in Fig.…”

Section: Ecs Transactions 28 (4) 3-11 (2010)mentioning

confidence: 99%

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Studies of Electron Trapping in ZnO Semiconductor

et al. 2010

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It has been recently discovered that electron injection into Phosphorus-, Lithium-, Antimony-or Nitrogen-doped ZnO semiconductor, using electron beam from a Scanning Electron Microscope, as well as a forward bias application to the p-n junction or Schottky barrier, leads to a multiple-fold increase of minority carrier diffusion length and lifetime (1-4). It has also been demonstrated that forward biasing a ZnO-based photovoltaic detector results in a several-fold responsivity enhancement due to a longer minority carrier diffusion length in the detector's p-region as a result of electron injection (5, 6). The observed electron injection effects were attributed to the charging of the metastable centers associated with the above-referenced impurities.With p-type doping of ZnO becoming possible, it is very likely that minority carrier (bipolar) devices such as LEDs, laser diodes, and transparent p-n junctions can be achieved in the near future (7,8,9). Besides effective p-type doping and robust ohmic contact fabrication, attaining the optimum performance of bipolar devices hinges upon overcoming an additional challenge -a short minority carrier diffusion length (usually ≤ 1µm), which is common to direct band gap semiconductors. Given the fact that the diffusion length is a critical parameter defining performance of p-n junction devices, it is imperative to find ways for its improvement. Our recent findings indicate that the latter parameter in ZnO can be noticeably enhanced by electron injection. The observed novel effect was attributed to electron trapping on impurity-related levels (10, 11). Electron injection in bulk ZnO substratesThe experiments were carried out on commercially available (Tokyo Denpa (TD)) bulk ZnO substrates grown by hydrothermal technique. Secondary Ion Mass Spectroscopy (SIMS) measurements performed on these substrates revealed the presence of lithium (Li) in the crystal on the level of ~ 4x10 16 cm -3 (Li is often added to ZnO to increase the resistivity of initially n-type samples) (12). Room temperature Hall measurements showed the samples to be a weak n-type with an electron concentration of ~ 10 14 cm -3 and mobility of ~ 150 cm 2 /Vs. The samples under investigation were cleaved perpendicular to c-plane thus exposing the non-polar a-plane of ZnO. This was motivated by the observations that the latter crystallographic plane results in a better quality of Schottky contacts, as opposed to those deposited on the c-plane. Schottky barriers were, therefore, fabricated by electron beam evaporation of 100 nm-thick Au layer on ZnO a-plane and subsequent lift-off.The experiments were carried out in-situ in a Philips XL30 Scanning Electron Microscope, which is integrated with a Gatan MonoCL3 cathodoluminescence system allowing wavelength-dependent and temperature-dependent optical measurements. A sample temperature in the cathodoluminescence measurements varied from 25 to 125 o C. For each temperature, periodic CL measurements were carried out under an SEM magnification of 4,000 at different locat...

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Section: Electron Injection In Bulk Zno Substratesmentioning

confidence: 99%

Section: Ecs Transactions 28 (4) 3-11 (2010)mentioning

confidence: 99%

Studies of Electron Trapping in ZnO Semiconductor

et al. 2010

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“…23 As L is proportional to the square root of lifetime and depends linearly on t, 22,23,26 the inverse CL intensity, 1 / I, which is also proportional to (larger determines longer nonequilibrium carrier stay in the band, and, as a result, lower rate of recombination), should depend on duration of electron injection quadratically. 23 As L is proportional to the square root of lifetime and depends linearly on t, 22,23,26 the inverse CL intensity, 1 / I, which is also proportional to (larger determines longer nonequilibrium carrier stay in the band, and, as a result, lower rate of recombination), should depend on duration of electron injection quadratically.…”

Section: Exhibits a Continuous Decay With Increasing Duration Of Elecmentioning

confidence: 99%

“…26 It is assumed that ⌬E A for both competing factors are close to each other. Note that the factor of 2 before the thermal energy kT comes from the two competing factors: R dependence on duration of electron injection ͓ϳexp͑⌬E A / kT͔͒ and on temperature ͓ϳexp͑−⌬E A / 2kT͔͒.…”

Section: Exhibits a Continuous Decay With Increasing Duration Of Elecmentioning

confidence: 99%

Minority carrier transport in p-type Zn0.9Mg0.1O doped with phosphorus

Lopatiuk

Burdett

Chernyak

et al. 2004

Applied Physics Letters

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Minority carrier diffusion length and lifetime in p-Zn 0.9 Mg 0.1 O doped with phosphorus were obtained from local electron beam irradiation measurements. The irradiation resulted in an increase of up to 25% in minority electron diffusion length from the initial value of ϳ2.12 m and in a simultaneous decrease of the peak near-bandedge cathodoluminescence intensity. The observed phenomena are attributed to charging of phosphorus-related deep acceptor level(s), which is consistent with the activation energy of 256± 20 meV found for the effect of electron injection in Zn 0.9 Mg 0.1 O.

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Photomodification of carrier lifetime and diffusivity in AlGaN epitaxial layers

Podlipskas

Aleksiejūnas

Наргелас

et al. 2016

Current Applied Physics

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Nonradiative recombination rate and diffusivity of nonequilibrium carriers were modified by intense laser pulses in AlGaN epilayers with Al content ranging from 16 to 71%. The epilayers were examined before and after the photomodification using light-induced transient grating and photoluminescence spectroscopy techniques. The photomodification resulted in (i) enhancement of the nonradiative recombination rate and (ii) large changes of the diffusion coefficient of the nonequilibrium carriers, without imposing any macroscopic structural damage to the epilayers. The photomodification effect on the recombination rate was stronger in the layers with higher Al content indicating the involvement of the Al atoms in this process. The carrier diffusivity exhibited a rapid initial increase as a consequence of the photomodification followed by a slow decline, as the photomodification duration was increased. The enhancement of the diffusion coefficient of up to 2.4 times was accompanied by 13% decrease in the carrier lifetime.

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The optical signature of electron injection in p-(Al)GaN

Cited by 8 publications

References 12 publications

Studies of Electron Trapping in ZnO Semiconductor

Studies of Electron Trapping in ZnO Semiconductor

Minority carrier transport in p-type Zn0.9Mg0.1O doped with phosphorus

Photomodification of carrier lifetime and diffusivity in AlGaN epitaxial layers

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