Structural and optical characterization of intrinsic GaN nanocolumns

Sánchez-Páramo, J.; Calleja, J.M.; Sánchez-García, M.Á.; Calleja, E.; Jahn, U.

doi:10.1016/s1386-9477(02)00305-3

Cited by 31 publications

(21 citation statements)

References 16 publications

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“…By varying the III/V ratio during the growth, one controls the density and the diameter of these self-ordered nanostructures: 6,15 the smaller the III/V ratio, the smaller the diameter, and the higher the density of NCs. The exceptional crystalline quality of the NCs has been verified previously by transmission electron microscopy 16 and Raman scattering studies, 8 also proving that they are strain-free. Concerning their morphology, Fig.…”

Section: Samples and Experimental Detailssupporting

confidence: 52%

“…Yet, the studied samples exhibit a very high crystalline quality and are unstrained. 8 Since these structures present a large surface-to-volume ratio, we believe that surface effects have to be taken into account. To support this suggestion, we remark that the energy and the wave function of the n = 1 level of a donor are indeed perturbed if the donor and the surface are separated by less than the donor Bohr radius, a D ͑3 nm for GaN͒.…”

Section: Time-integrated Photoluminescencementioning

confidence: 99%

“…[6][7][8] Alternative synthesis techniques are hydride vapor phase epitaxy 9 or metal-organic chemical vapor deposition. 10 NCs made of GaN, ͑Al,Ga͒N, and ͑In,Ga͒N as well as their heterostructures 11,12 can be grown on a wide variety of substrates, such as Si ͑001͒, 13 Si ͑111͒, 8 and sapphire, 6,7,14 with or without GaN buffer layer, the c-axis of the columns being perpendicular to the surface of the substrate. Even though the activity in this field has been quite significant in the past decade, rather little attention has been devoted to the detailed study of optical properties of pure GaN NCs, in relation to their particular geometry.…”

Section: Introductionmentioning

confidence: 99%

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Time-resolved spectroscopy on GaN nanocolumns grown by plasma assisted molecular beam epitaxy on Si substrates

Corfdir

Lefèbvre

Ristić

et al. 2009

Journal of Applied Physics

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A detailed study of excitons in unstrained GaN nanocolumns grown by plasma assisted molecular beam epitaxy on silicon substrates is presented. The time-integrated and time-resolved photoluminescence spectra do not depend significantly on the ͑111͒ or ͑001͒ Si surface used. However, an unusually high relative intensity of the two-electron satellite peak of the dominant donor-bound exciton line is systematically observed. We correlate this observation with the nanocolumn morphology determined by scanning electron microscopy, and therefore propose an interpretation based on the alteration of wave functions of excitonic complexes and of donor states by the proximity of the semiconductor surface. This explanation is supported by a model that qualitatively accounts for both relative intensities and time decays of the photoluminescence lines.

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Section: Samples and Experimental Detailssupporting

confidence: 52%

Section: Time-integrated Photoluminescencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time-resolved spectroscopy on GaN nanocolumns grown by plasma assisted molecular beam epitaxy on Si substrates

Corfdir

Lefèbvre

Ristić

et al. 2009

Journal of Applied Physics

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“…The growth of GaN nanocolumns was performed under N-rich conditions. 8,11 The Ga flux was controlled to a beam equivalent pressure of 2 ϫ 10 −7 Torr, which is approximately ten times smaller than that used for GaN epilayers ͑4 ϫ 10 −6 Torr͒. The power and flow rate of the N plasma source were 350 W and 2.0 sccm, respectively.…”

Section: Time-resolved and Time-integrated Photoluminescence Studies mentioning

confidence: 99%

“…11 In contrast, it is expected that the Q-discs are fully strained because the height of Q-discs are thin indicating that they would grow pseudomorphically, generating a strong piezoelectric field.…”

Section: Time-resolved and Time-integrated Photoluminescence Studies mentioning

confidence: 99%

Time-resolved and time-integrated photoluminescence studies of coupled asymmetric GaN quantum discs embedded in AlGaN barriers

Taylor

Rice

et al. 2005

Applied Physics Letters

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We have investigated exciton dynamics in asymmetric GaN quantum discs embedded in AlGaN barriers with an Al content of 50% using time-integrated and time-resolved micro-photoluminescence measurements. Emission from the quantum discs emerges at lower energy than that from the GaN nanocolumns, which suggests that GaN quantum discs are strongly affected by the built-in electric field. The lifetimes of localized excitons in quantum discs were obtained. Nonlinear emission from quantum discs under high excitation power was attributed to tunneling of carriers to larger discs from smaller discs.

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GaN‐based nanowires: From nanometric‐scale characterization to light emitting diodes

Bavencove

Tourbot

Pougeoise

et al. 2010

Physica Status Solidi (a)

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We studied and improved gallium nitride (GaN) nanowire (NW) based light emitting diodes (LEDs). PIN nanodiodes with and without InGaN/GaN multiple quantum wells (MQWs) were grown by molecular beam epitaxy (MBE) under N-rich conditions on n-doped Si(111) substrates. Thanks to the coalescence of the p-type region of the NWs grown at low temperature, an autoplanarization process has been performed to obtain LEDs. Ni/Au top contacts have been deposited and patterned in order to bias the devices. A multiple-scale characterization approach has been carried out through the comparison of localized cathodoluminescence (CL) and macroscopic electroluminescence (EL) spectra. It shows that the EL emission of PIN-based LED at room temperature is related to defects in the p-type region of the NWs. In order to enhance the radiative recombinations of NW-based LEDs, we have first added InGaN/GaN MQWs, and secondly an electron blocking layer (EBL) has been inserted between the MQWs and the p-type zone of the NWs. The LED with EBL exhibited an emission band at 420 nm. The blue-shift of this emission band with increasing injected current is attributed to quantum confined Stark effect (QCSE) and evidences the radiative emission of InGaN/GaN MQWs. At 50 mA dc current, this improved NW-based LED emits about 500 times more light than the heterostructure without EBL.

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Structural and optical characterization of intrinsic GaN nanocolumns

Cited by 31 publications

References 16 publications

Time-resolved spectroscopy on GaN nanocolumns grown by plasma assisted molecular beam epitaxy on Si substrates

Time-resolved spectroscopy on GaN nanocolumns grown by plasma assisted molecular beam epitaxy on Si substrates

Time-resolved and time-integrated photoluminescence studies of coupled asymmetric GaN quantum discs embedded in AlGaN barriers

GaN‐based nanowires: From nanometric‐scale characterization to light emitting diodes

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