Cathodoluminescence studies of the electron injection-induced effects in GaN

Chernyak, Leonid; Burdett, William; Klimov, Mikhail; Osinsky, A.

doi:10.1063/1.1578514

Cited by 30 publications

(26 citation statements)

References 15 publications

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“…This demonstrates that exposure to the electron beam results in the increase of carrier lifetime (), since I CL is proportional to 1/. Similar phenomena were also observed in GaN, where the decay of NBE CL intensity occurred concomitantly with increasing diffusion length [38,50,51].…”

Section: Optical Studies Of Znsupporting

confidence: 57%

“…Fig. 10 (center)), with the rates of diffusion length increase ranging from ~13% to ~30% per 1000 s. This appears to be a common occurrence in wide bandgap semiconductors doped with species that create deep acceptor levels, as similar observations were made in (Al)GaN doped with Mg, Mn, Fe, and C [39,50,51]. It is also noteworthy that similar experiments conducted on bulk ZnO without any intentional dopants did no show any significant changes in minority carrier diffusion length [38].…”

Section: Influence Of Electron Trapping On Minority Carrier Diffusionmentioning

confidence: 51%

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Cathodoluminescence Studies of Electron Injection Effects in Wide-Band-Gap Semiconductors

Schwarz¹,

Chernyak²,

Flitsiyan³

2012

Cathodoluminescence

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Section: Optical Studies Of Znsupporting

confidence: 57%

Section: Influence Of Electron Trapping On Minority Carrier Diffusionmentioning

confidence: 51%

Cathodoluminescence Studies of Electron Injection Effects in Wide-Band-Gap Semiconductors

Schwarz¹,

Chernyak²,

Flitsiyan³

2012

Cathodoluminescence

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“…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%

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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“…The phenomenon of external electron irradiation has been previously studied and reported in (14,17,18). The internal electron irradiation by Compton electrons is similar to the irradiation by external electrons (produced, for example, by electron beam.…”

Section: Resultsmentioning

confidence: 94%

Low and moderate dose gamma-irradiation and annealing impact on electronic and electrical properties of AlGaN/GaN high electron mobility transistors

Yadav

Flitsiyan

Chernyak

et al. 2015

Radiation Effects and Defects in Solids

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2015): Low and moderate dose gamma-irradiation and annealing impact on electronic and electrical properties of AlGaN/GaN high electron mobility transistors, Radiation Effects and Defects in Solids: Incorporating Plasma Science and Plasma Technology,To understand the effects of 60 Co gamma-irradiation, systematic studies were carried out on n-channel AlGaN/GaN high electron mobility transistors. Electrical testing, combined with electron beam-induced current measurements, was able to provide critical information on defects induced in the material as a result of gamma-irradiation. It was shown that at low gamma-irradiation doses, the minority carrier diffusion length in AlGaN/GaN exhibits an increase up to ∼ 300 Gy. The observed effect is due to longer minority carrier (hole) life time in the material's valence band as a result of an internal electron irradiation by Compton electrons. However, for larger doses of gamma irradiation (above 400 Gy), deteriorations in transport properties and device characteristics were observed. This is consistent with the higher density of deep traps in the material's forbidden gap induced by a larger dose of gamma-irradiation. Moderate annealing of device structures at 200°C for 25 min resulted in partial recovery of transport properties and device performance.

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Cathodoluminescence studies of the electron injection-induced effects in GaN

Cited by 30 publications

References 15 publications

Cathodoluminescence Studies of Electron Injection Effects in Wide-Band-Gap Semiconductors

Cathodoluminescence Studies of Electron Injection Effects in Wide-Band-Gap Semiconductors

Studies of Electron Trapping in ZnO Semiconductor

Low and moderate dose gamma-irradiation and annealing impact on electronic and electrical properties of AlGaN/GaN high electron mobility transistors

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