Optical density of states in ultradilute GaAsN alloy: Coexistence of free excitons and impurity band of localized and delocalized states

Bhuyan, Sumi; Das, Sanat Kr.; Dhar, S.; Pal, Bipul; Bansal, Bhavtosh

doi:10.1063/1.4886178

Cited by 16 publications

(6 citation statements)

References 33 publications

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“…For higher lattice temperatures (T > 60 K), the dependence of the hot carriers temperature on the lattice temper ature is nearly linear to a good approximation. Similar behavior was detected also in other materials like PbS quantum dots [21], in GaSb-based multi quantum wells [22], in GaAs 1−x N x [23], and in Si [24]. Hot carriers would usually quickly undergo carrier-phonon (mostly LO-phonons) interaction and release the excess energy above the bandgap as lattice vibration through emission of phonons on the order of picoseconds.…”

Section: Temperature Dependence Of Pl Emission and Carrier Localizati...supporting

confidence: 73%

Observation of band gap fluctuations and carrier localization in Cu₂CdGeSe₄

Krustok

Raadik

Kaupmees

et al. 2019

J. Phys. D: Appl. Phys.

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Excitation power and temperature dependences of the steady-state photoluminescence (PL) spectra are studied in polycrystalline Cu 2 CdGeSe 4 (CCGSe) containing a mixture of orthorhombic and tetragonal phases. The low-temperature excitation power dependences of the PL peak shape with a peak position at about 1.17 eV indicate a state filling effect. Reflectivity measurements revealed band gap energies 1.257 eV and 1.223 eV at 10 K and 300 K, respectively. The temperature dependences of the peak energy and linewidth showed a 'S-shaped' and 'V-shaped' behavior, respectively, and are well explained by the localized carriers model where band gap fluctuations play a crucial role. The asymmetric PL band shape analysis indicates the presence of hot carriers having a temperature about 75 K higher than the lattice temperature. It is shown that the low-temperature PL emission is due to recombination of localized electrons with holes captured by the deep acceptor defect Cu Cd with a depth E A = 80 meV.

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Section: Temperature Dependence Of Pl Emission and Carrier Localizati...supporting

confidence: 73%

Observation of band gap fluctuations and carrier localization in Cu₂CdGeSe₄

Krustok

Raadik

Kaupmees

et al. 2019

J. Phys. D: Appl. Phys.

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“…A tentative explanation of the observed discrepancies between the band gap energies obtained from SPV and PL results is presented below. It is well known that the N atoms in dilute nitrides give origin of a series of defect states, some of which are in the band gap [20,21,44]. The light intensity in the SPV experiment is much lower than that in the PL one.…”

Section: Surface Photovoltage Spectroscopymentioning

confidence: 95%

“…This allows obtaining thick layers of high quality material in terms of lifetime, mobility and freedom from defects, suitable for solar cell applications. In spite of this there have been few reports on Ga(In)AsN layers grown by LPE [20][21][22][23][24] and even fewer for the LPE-grown pentanary compound InGaAsSbN [25]. Therefore, it is important to study such materials by various complementary experimental techniques.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sb in thick InGaAsSbN layers grown by liquid phase epitaxy

Milanova

Asenova

Shtinkov

et al. 2018

Journal of Crystal Growth

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Dilute nitride InGaAsSbN layers grown by low-temperature liquid phase epitaxy are studied in comparison with quaternary InGaAsN layers grown at the same growth conditions to understand the effect of Sb in the alloy. The lattice mismatch to the GaAs substrate is found to be slightly larger for the InGaAsNSb layers, which is explained by the large atomic radius of Sb. A reduction of the band gap energy with respect to InGaAsN is demonstrated by means of photoluminescence (PL), surface photovoltage (SPV) spectroscopy and tight-binding calculations. The band-gap energies determined from PL and ellipsometry measurements are in good agreement, while the SPV spectroscopy and the tight-binding calculations provide lower values. Possible reasons for these discrepancies are discussed. The PL spectra reveal localized electronic states in the band gap near the conduction band edge, which is confirmed by SPV spectroscopy. The analysis of the power dependence of the integrated PL has allowed determining the dominant radiative recombination mechanisms in the layers. The values of the refraction index in a wide spectral region are found to be higher for the Sb containing layers.

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“…4 To understand these complex properties, several studies have been performed on bulk GaNAs or GaNAs/GaAs quantum wells (QWs) employing absorption techniques like photoreflectance [5][6][7] or surface photovoltage spectroscopy, 8 as well as emission techniques such as photoluminescence (PL) measurement. 9,10 Only few studies have combined emission and absorption techniques. 3,11 From previous experiments the dependence of GaN x As 1−x band gap energy and the behavior of the confined ground state energy in GaNAs/GaAs QWs have been studied.…”

Section: Introductionmentioning

confidence: 99%

Optical transitions in GaNAs quantum wells with variable nitrogen content embedded in AlGaAs

et al. 2016

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We investigate the optical transitions of GaNxAs1−x quantum wells (QWs) embedded in wider band gap AlGaAs. A combination of absorption and emission spectroscopic techniques is employed to systematically investigate the properties of GaNAs QWs with N concentrations ranging from 0 – 3%. From measurement of the photocurrent spectra, we find that besides QW ground state and first excited transition, distinct increases in photocurrent generation are observed. Their origin can be explained by N-induced modifications in the density of states at higher energies above the QW ground state. Photoluminescence experiments reveal that peak position dependence with temperature changes with N concentration. The characteristic S-shaped dependence for low N concentrations of 0.5% changes with increasing N concentration where the low temperature red-shift of the S-shape gradually disappears. This change indicates a gradual transition from impurity picture, where localized N induced energy states are present, to alloying picture, where an impurity-band is formed. In the highest-N sample, photoluminescence emission shows remarkable temperature stability. This phenomenon is explained by the interplay of N-induced energy states and QW confined states.

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Optical density of states in ultradilute GaAsN alloy: Coexistence of free excitons and impurity band of localized and delocalized states

Cited by 16 publications

References 33 publications

Observation of band gap fluctuations and carrier localization in Cu₂CdGeSe₄

Observation of band gap fluctuations and carrier localization in Cu₂CdGeSe₄

Effect of Sb in thick InGaAsSbN layers grown by liquid phase epitaxy

Optical transitions in GaNAs quantum wells with variable nitrogen content embedded in AlGaAs

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Optical density of states in ultradilute GaAsN alloy: Coexistence of free excitons and impurity band of localized and delocalized states

Cited by 16 publications

References 33 publications

Observation of band gap fluctuations and carrier localization in Cu2CdGeSe4

Observation of band gap fluctuations and carrier localization in Cu2CdGeSe4

Effect of Sb in thick InGaAsSbN layers grown by liquid phase epitaxy

Optical transitions in GaNAs quantum wells with variable nitrogen content embedded in AlGaAs

Contact Info

Product

Resources

About

Observation of band gap fluctuations and carrier localization in Cu₂CdGeSe₄

Observation of band gap fluctuations and carrier localization in Cu₂CdGeSe₄