Magnetoluminescence and Resonant Electronic Raman Scattering Investigation of Donors and Excitons in Hydride Vpe and Mocvd GaN

1997 ◽  
Vol 482 ◽  
Author(s):  
B. J. Skromme ◽  
J. Jayapalan ◽  
D. Wang ◽  
O. F. Sankey
Keyword(s):  
Binding Energy ◽  
Raman Scattering ◽  
Free Exciton ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Neutral Donor ◽  
Electronic Raman Scattering ◽  
Si Doped ◽  
Nonperturbative Theory ◽  
Donor Species

AbstractThe donor and exciton states in ultra high-quality heteroepitaxial GaN grown by hydride vapor phase epitaxy (HVPE) and metalorganic chemical vapor deposition (MOCVD) on sapphire substrates are investigated using low temperature photoluminescence (PL), reflectance, magnetospectroscopy in fields up to 12 T, and resonant electronic Raman scattering (RERS). The A free exciton is confirmed to have a binding energy of about 26.4 meV, independent of strain in the material. Bound n=2 exciton peaks are distinguished in the PL spectrum by their thermalization and sample dependence. The Si donor is shown to have a binding energy of about 21 meV using Si-doped HVPE samples grown at Epitronics. Up to five additional residual donor species are observed when comparing various HVPE and MOCVD samples. Pronounced temperaturedependence of the two-electron satellites is observed, suggesting the existence of unresolved excited rotator states of the neutral donor-bound exciton. Highly resolved magnetic splitting patterns are observed in the two-electron satellites. A nonperturbative theory of these donor splittings is developed, including anisotropy. Resonant electronic Raman scattering from residual donors is reported, and yields improved linewidths compared to PL.

scholarly journals Photoluminescence, Magnetospectroscopy, and Resonant Electronic Raman Studies of Heteroepitaxial Gallium Nitride

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
B.J. Skromme
Keyword(s):  
Magnetic Field ◽  
Binding Energy ◽  
Room Temperature ◽  
Free Exciton ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Chemical Treatments ◽  
Electronic Raman Scattering ◽  
Donor States

Optical spectroscopy, including low and room temperature photoluminescence (PL), reflectance, PL measurements in high magnetic fields up to 12 T, and resonantly-enhanced electronic Raman scattering (RERS) in zero and high magnetic field, has been used to investigate exciton and impurity states and surface recombination in high quality heteroepitaxial GaN grown on sapphire and SiC. Theoretical finite-difference calculations of the donor states as a function of magnetic field have been carried out for comparison, including the effects of anisotropy in the effective mass and dielectric constant. Up to six residual donor species are observed in material grown by hydride vapor phase epitaxy (HVPE) and metalorganic chemical vapor deposition (MOCVD) from their n=2 and n=3 two-electron satellites observed in PL and by RERS. The donor-related nature of the relevant transitions is confirmed from their magnetic field dependence, and the spectral resolution is improved at high fields. The Si donor level is determined to have a binding energy of about 21 meV from observation of its two-electron satellite in lightly Si-doped HVPE material. The free exciton binding energy is shown to be about 26.4 meV, independent of strain, based on observations of the n=2 free exciton. The room temperature band-edge PL peak is confirmed to be free excitonic in nature, based on its linewidth and on comparison with simple reflectance measurements. Reflectance from the edge of a thick HVPE layer shows clear evidence of A, B, and C excitons obeying the relevant selection rules at both low and room temperature. Surface chemical treatments are shown to have substantial effects on room temperature PL efficiency. Passivation with ammonium or sodium sulfide solutions, in particular, yields increases in PL efficiency by a factor of five to seven over air-exposed surfaces. The passivation effect is stable in air, lasting at least one month.

Photoluminescence, Reflectance, and Magnetospectroscopy of Shallow Excitons in GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
B. J. Skromme ◽  
H. Zhao ◽  
B. Goldenberg ◽  
H. S. Kong ◽  
M. T. Leonard ◽  
...  
Keyword(s):  
Binding Energy ◽  
Molecular Beam ◽  
Free Exciton ◽  
Chemical Vapor ◽  
Exciton Binding Energy ◽  
Exciton Peak ◽  
Neutral Donor ◽  
Gas Source ◽  
Donor Binding Energy ◽  
First Time

ABSTRACTWe report several new aspects of the excitonic properties of heteroepitaxial GaN grown on sapphire or 6H-SiC. In particular, we observed the n = 2 free exciton associated with both A and B excitons (which are distinct from the n = 1 C exciton) using reflectance and 1.7 K photoluminescence. We also studied the behavior of the n = 2 A-exciton using magnetoluminescence in fields up to 12 T. The large diamagnetic shift and splitting positively confirm the identification, yielding an exciton binding energy of about 26.4 meV. Several previous identifications of the n = 2 free exciton yielding a smaller exciton binding energy are probably in error, based on our results. We have also detected the two-electron replica of the neutral donor-bound exciton for the first time in GaN and observed its splitting pattern in magnetic fields up to 12 T. This feature is 22 meV below the principal neutral donor-bound exciton peak, independently of strain shifts in the overall spectrum. It yields a precise donor binding energy of 29 meV for the shallow residual donor in material grown by metalorganic chemical vapor deposition and gas-source molecular beam epitaxy, considerably smaller than that of the residual donor reported earlier in hydride vapor phase epitaxial material (about 35.5 meV).

Deposition of Zinc Oxide Thin Films Using a Surface Reaction on Platinum Nanoparticles

2011 ◽  
Vol 1315 ◽  
Author(s):  
Kanji Yasui ◽  
Hitoshi Miura ◽  
Hiroshi Nishiyama
Keyword(s):  
Free Exciton ◽  
Exothermic Reaction ◽  
Chemical Vapor ◽  
Band Edge ◽  
Chemical Vapor Deposition Method ◽  
Zno Films ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Neutral Donor ◽  
Pl Spectra

ABSTRACTA new chemical vapor deposition method for the growth of ZnO films using the reaction between dimethylzinc (DMZn) and thermally excited H2O produced by a Pt-catalyzed H2–O2 reaction was investigated. The thermally excited H2O molecules formed by the exothermic reaction of H2 and O2 on the catalyst were ejected from a fine nozzle into the reaction zone and allowed to collide with DMZn ejected from another fine nozzle. The ZnO films were grown directly on a-plane (11-20) sapphire substrates at substrate temperatures of 773-873 K with no buffer layer. X-ray diffraction patterns exhibited intense (0002) and (0004) peaks from the ZnO(0001) index plane. The smallest full width at half maximum (FWHM) value of the ω- rocking curve of ZnO(0002) was less than 0.1º. The largest Hall mobility and the smallest residual carrier concentration of the ZnO films were 169 cm2V−1s−1 and 1.7×1017 cm−3, respectively. Photoluminescence (PL) spectra at room temperature exhibited a band edge emission at 3.29 eV, with a FWHM of 104 meV. Green luminescence from deeper levels was generally about 1.5% of the band edge emission intensity. PL spectra at 5 K showed a strong emission peak at 3.3603 eV, attributed to the neutral donor-bound exciton Dºx. The FWHM was as low as 1.0 meV. Free exciton emissions also appeared at 3.3757 eV (FXA, n=1) and 3.4221 eV (FXA, n=2).

scholarly journals Characteristics of Deep Centers Observed in n-GaN Grown by Reactive Molecular Beam Epitaxy

2000 ◽  
Vol 5 (S1) ◽  
pp. 943-949 ◽  
Author(s):  
Z-Q. Fang ◽  
D. C. Look ◽  
Wook Kim ◽  
H. Morkoç
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Deep Level ◽  
Strong Electric Field ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Electric Field Effects ◽  
Deep Centers ◽  
Si Doped ◽  
Transient Spectroscopy

Deep centers in Si-doped n-GaN samples grown on sapphire by reactive molecular beam epitaxy, using different ammonia flow rates (AFRs), have been studied by deep level transient spectroscopy. In addition to five electron traps, which were also found in n-GaN layers grown by both metalorganic chemical-vapor deposition and hydride vapor-phase epitaxy, two new centers C1 (0.43-0.48 eV) and E1 (0.25 eV) have been observed. C1, whose parameters show strong electric-field effects and anomalous electron capture kinetics, might be associated with dislocations. E1, which is very dependent on the AFR, exhibits an activation energy close to that of a center created by electron irradiation and is believed to be a defect complex involving VN.

Characteristics of Deep Centers Observed in n-GaN Grown by Reactive Molecular Beam Epitaxy

1999 ◽  
Vol 595 ◽  
Author(s):  
Z-Q. Fang ◽  
D. C. Look ◽  
Wook Kim ◽  
H. Morkoç
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Deep Level ◽  
Strong Electric Field ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Electric Field Effects ◽  
Deep Centers ◽  
Si Doped ◽  
Transient Spectroscopy

AbstractDeep centers in Si-doped n-GaN samples grown on sapphire by reactive molecular beam epitaxy, using different ammonia flow rates (AFRs), have been studied by deep level transient spectroscopy. In addition to five electron traps, which were also found in n-GaN layers grown by both metalorganic chemical-vapor deposition and hydride vapor-phase epitaxy, two new centers C1 (0.43-0.48 eV) and E1 (0.25 eV) have been observed. C1, whose parameters show strong electric-field effects and anomalous electron capture kinetics, might be associated with dislocations. E1, which is very dependent on the AFR, exhibits an activation energy close to that of a center created by electron irradiation and is believed to be a defect complex involving VN.

Comparative Investigation of Photoluminescence of In- and Si- doped GaN/AlGaN Multi-Quantum Wells

2002 ◽  
Vol 719 ◽  
Author(s):  
W. H. Sun ◽  
L. S. Wang ◽  
S. J. Chua
Keyword(s):  
Quantum Wells ◽  
Resonance Effect ◽  
Free Exciton ◽  
Chemical Vapor ◽  
Comparative Investigation ◽  
Exciton Peak ◽  
Phonon Replica ◽  
Temperature Ranges ◽  
Si Doped ◽  
Localized Excitons

AbstractThe GaN/AlGaN multi-quantum-wells (MQWs) have been grown via metalorganic chemical vapor deposition (MOCVD). Micro-Photoluminescence (PL) measurement has been performed on non-, In- and Si- doped GaN/AlGaN multi-quantum-well samples in the temperature ranges of 90-300 K. In the non-doped GaN/AlGaN multi-quantum-wells we observed the free exciton peak at 3.4587 eV at 90 K. Other exciton related peaks are located at 3.4346, 3.4177, 3.394, 3.3129eV, which are probably associated with the strongly localized excitons involving the defects. In In-doped GaN/AlGaN MQWs, the free exciton peaks have a slight red-shift from 3.4712 to 3.4629 eV, but the PL intensities become stronger with increasing trimethylindium (TMIn) flow from 10.6 to 42.6-νmol/min. With Si-doping in the well layers, photoluminescence exhibits an envelope of exciton bands ranged from 3.4796eV (free exciton) to 3.43915eV. The excitonic peaks in the bands vary in intensity and position with sample temperature. In addition, we have also observed the LO phonon replica of AlGaN interacted by the laser line due to the resonance effect.

Electronic Raman Scattering from Mg-Doped Wurtzite GaN

1999 ◽  
Vol 595 ◽  
Author(s):  
K.T. Tsen ◽  
C. Koch ◽  
Y. Chen ◽  
H. Morkoc ◽  
J. Li ◽  
...  
Keyword(s):  
Binding Energy ◽  
Raman Scattering ◽  
Temperature Dependence ◽  
Excited States ◽  
Experimental Results ◽  
Electronic Raman Scattering ◽  
First Time ◽  
Broad Structure ◽  
Mg Doped

AbstractElectronic Raman scattering experiments have been carried out on both MBE and MOCVD-grown Mg-doped wurtzite GaN samples. Aside from the expected Raman lines, a broad structure (FWHM ≅ 15cm−1) observed for the first time at around 841cm−1 isattributed to the electronic Raman scattering from neutral Mg impurities in Mg-dopedGaN. From the analysis of the temperature-dependence of this electronic Ramanscattering signal binding energy of the Mg impurities in wurtzite GaN has been found to be Eb ≅ 172 ± 20meV. These experimental results demonstrate that the energy between the ground and first excited states of Mg impurities in wurtzite GaN is about 3/5 of its binding energy.

scholarly journals Electronic Raman Scattering in Suspended Semiconducting Carbon Nanotube

2020 ◽  
Vol 11 (24) ◽  
pp. 10497-10503
Author(s):  
Yuecong Hu ◽  
Shaochuang Chen ◽  
Xin Cong ◽  
Sida Sun ◽  
Jiang-bin Wu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Raman Scattering ◽  
Electronic Raman Scattering
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