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1.
A theoretical investigation of the band alignment of type-I direct band gap dilute nitride phosphide alloy of GaN_xAs_yP_(1-x-y)/GaP quantum wells on GaP substrates
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The GaP-based dilute nitride direct band gap material Ga(NAsP) is gaining importance due to the monolithic integra- tion of laser diodes on Si microprocessors. The major advantage of this newly proposed laser material system is the small lattice mismatch between GaP and Si. However, the large threshold current density of these promising laser diodes on Si substrates shows that the carrier leakage plays an important role in Ga(NAsP)/GaP QW lasers. Therefore, it is necessary to investigate the band alignment in this laser material system. In this paper, we present a theoretical investigation to optimize the band alignment of type-I direct band gap GaNxAsyP1-x-y/GaP QWs on GaP substrates. We examine the effect of nitrogen (N) concentration on the band offset ratios and band offset energies. We also provide a comparison of the band alignment of type-I direct band gap GaNxAsyP1-x-y/GaP QWs with that of the GaNxAsyP1-x-y/Al2Ga1-2P QWs on GaP substrates. Our theoretical calculations indicate that the incorporations of N into the well and AI into the barrier improve the band alignment compared to that of the GaAsP/GaP QW laser heterostructures. 相似文献
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The electronic structure and optical gain of InAsPN/GaP(N) quantum dots (QDs) are investigated in the framework of the effective-mass envelope function theory. The strain distribution is calculated using the valence force field (VFF) method. With GaP barrier, for smaller InAsPN QDs, the minimum transition energy may occur at a lower phosphorous (P) composition, but for larger QDs, the transition energy increases as P composition increases due to the increased bandgap of alloy QDs. When the nitrogen (N) composition increases, the transition energy decreases due to the stronger repulsion between the conduction band (CB) and the N resonant band, and the transition matrix element (TME) is more affected by the transition energy rather than N–CB mixing. To obtain laser materials with a lattice constant comparable to Si, we incorporated 2% of N into the GaP barrier. With this GaP0.98N0.02 barrier, the conduction band offset is reduced, so the quantum confinement is lower, resulting in a smaller transition energy and longer wavelength. At the same time, the TME is reduced and the optical gain is less than those without N in the barrier at a low carrier density, but the peak gain increases faster when the carrier density increases. Finally it can surpass and reach a greater saturation optical gain than those without N in the barrier. This shows that incorporating N into GaP barriers is an effective way to achieve desirable wavelength and optical gain. 相似文献
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Low temperature near band-edge absorption and luminescence spectra of Si-doped n-type GaP are reported. Electrical and optical evidence is presented that these spectra are due to the creation and decay of excitons bound to neutral Si donors on Ga sites. Several zero-phonon transitions, each with strong replications by momentum conserving phonons, were observed in both absorption and luminescence. From these measurements it is concluded that the ground state of the SiGa donor is split into two sublevels 0.6 meV apart. Crystals containing a sufficiently low concentration of S to be suitable for a reliable analysis of temperature-dependent Hall-effect measurements were selected by combining 300°K Hall-effect data with low temperature S-exciton absorption data. The electrical measurements support the identification of Si as the main shallow donor. Moreover, it is concluded from these measurements that the degeneracy of the ground state of a Ga-site donor is 3 times that of a P-site donor, in agreement with theoretical expectations. 相似文献
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The luminescence decay times of NNi-pair emission are found to decrease when the photoexcitation density is increased from several W/cm2 to 106–107 W/cm2. For lightly N-doped GaP, the reduction is typically from 3000 to 30 nsec (A-line, low temperature); for heavily N-doped GaP it is from about 1000 nsec to a few nanoseconds. From this decay time reduction the onset of a new recombination mechanism is concluded. No mechanism is likely to explain previously reported high gain values for GaP : N. 相似文献
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Alain Rolland Laurent Pedesseau Jacky Even Samy Almosni Cedric Robert Charles Cornet Jean Marc Jancu Jamal Benhlal Olivier Durand Alain Le Corre Pierre Rale Laurent Lombez Jean-Francois Guillemoles Eric Tea Sana Laribi 《Optical and Quantum Electronics》2014,46(10):1397-1403
In this paper, we present a comprehensive study of high efficiencies tandem solar cells monolithically grown on a silicon substrate using GaAsPN absorber layer. InGaAs(N) quantum dots and GaAsPN quantum wells have been grown recently on GaP/Si susbstrate for applications related to light emission. For photovoltaic applications, we consider the GaAsPN diluted nitride alloy as the top junction material due to both its perfect lattice matching with Si and ideal bandgap energy for current generation in association with the Si bottom cell. Numerical simulation of the top cell is performed. The effect of layer thicknesses and doping on the cell efficiency are evidenced. In these structures a tunnel junction (TJ) is needed to interconnect both the top and bottom sub-cells. We compare the simulated performances of different TJ structures and show that the GaP(n+)/Si(p+) TJ is promising to improve performances of the current–voltage characteristic. 相似文献
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利用X射线光电子能谱(XPS)深度剖析方法对气体源分子束外延(GS-MBE)生长的GaP/Si异质结构进行了详细的分析.其结果表明:(1)外延层内Ga、P光电子峰与GaP相相符,且组份分布均匀,为正化学比GaP.(2)在不同富PH3流量条件下生长的样品,其表面富P量稍有不同,而GaP外延层内的测试结果相同.界面也未见有P的富集.(3)XPS剖析至GaP/Si界面附近,随外延层界面向衬底过渡,Si2p光电子峰向高结合能方向移动,且其结合能高于原衬底p型Si,接近于n型Si.但Ga、P光电子峰未发现有明显能移.(4)在XPS检测限内,外延层内和界面都未见有C、O等沾污.这一研究表明:无污染的本底超高真空、相对过剩的富3生长环境、成功的Si衬底清洗方法等措施保证了GS-MBE生长出正化学比GaP/Si外延异质结构. 相似文献
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C.O. Rodriguez 《Solid State Communications》1983,46(1):11-15
Total energies are calculated for crystalline Si and GaP within the local-density functional formalism using first principles non-local pseudopotentials. Ground state structural properties (total energy, bulk modulus and lattice constant) are obtained for Si and GaP and are in good agreement with experimental values (differences < 6%). Si is used as a test and compared with other theoretical calculations. 相似文献
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Anion antisite defects in semi-insulating GaP single crystals (doped with group V atoms) are investigated with optically detected electron paramagnetic resonance and electron nuclear double resonance (ODEPR and ODENDOR) ODEPR and ODENDOR are measured as microwave- and microwave- and rf-induced changes of the magnetic circular dichroism of the optical absorption (MCDA), respectively. In GaP: V two P antisite defects are found in about equal concentration which within ENDOR precision have tetrahedral site symmetry with respect to the nearest P ligands. The two PGaP4 defects have only slightly differentg-factors and31P superhyperfine interactions, but differ by one order of magnitude in their spin-lattice relaxation times. Their optical properties are also different from those of the PGaP4 defects reported earlier in GaP: Cr. It is concluded that there is no experimental prove yet. that any of the PGaP4 defects hitherto observed in GaP in an isolated PGaP4 defect which is not associated with another defect to form an antisite related defect complex. 相似文献
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L.A. Golovan G.I. Petrov G.Y. Fang V.A. Melnikov S.A. Gavrilov A.M. Zheltikov V.Y. Timoshenko P.K. Kashkarov V.V. Yakovlev C.F. Li 《Applied physics. B, Lasers and optics》2006,84(1-2):303-308
Nonlinear-optical interactions, such as second-harmonic and sum-frequency generation and coherent anti-Stokes Raman spectroscopy
(CARS), are investigated in porous GaP for the first time by means of a novel laser source based on mode-locked picosecond
Nd3+:YVO4 laser and subsequent continuum generation in an optical fiber. The efficiency of the former two nonlinear optical processes
is shown to be strongly dependent on the wavelengths of the interacting waves and tends to increase with the decrease of the
excitation wavelength. The power of the generated second-harmonic and sum-frequency increases by a factor of 2 and 30, respectively,
compared to the crystalline GaP. In contrast, the CARS signal in porous GaP is found to be less efficient than one in crystalline
GaP. The observed results are explained in terms of competition of the phase-matching effects in GaP nanocrystals and the
enhanced photon lifetime in scattering porous GaP layers.
PACS 42.25.Dd; 42.65.Ky; 42.70.Nq; 81.07.Bc 相似文献
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使用基于自旋局域密度泛函理论的第一性原理方法对3d过渡金属(TM=V,Cr,Mn,Fe,Co和Ni)掺杂的Ⅲ-Ⅴ族半导体(GaAs和GaP)的电磁性质进行了计算.结果发现:用V,Cr和Mn掺杂时体系将出现铁磁状态,而Fe掺杂时将出现反铁磁状态,Co和Ni掺杂时,其磁性则不稳定.其中,Cr掺杂的GaAs和GaP将可能是具有较高居里温度的稀磁半导体(DMS).在这些DMS系统中,V离子的磁矩大于理论期待值,Fe,Co和Ni离子的磁矩小于理论期待值,Cr和Mn离子的磁矩与期待值的差距取决于晶体的对称性以及磁性离子的能带分布.此外,使用Si和Mn共同对Ⅲ-Ⅴ族半导体进行掺杂,将有利于DMS表现为铁磁状态,并可以使体系的TC进一步提高.
关键词:
稀磁半导体
过渡金属
掺杂
共掺杂 相似文献
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The chemical compositions of two types of protective oxide films on single crystal GaP have been studied by Rutherford backscattering (2 MeV He+) combined with ion channeling. Films of 350–1400 Å thickness were grown by immersing GaP slices in hydrogen peroxide, with or without externally applied anodic bias. Films grown by a galvanic coupling process have compositions of about 1:1·1:4·5 (Ga:P:O) and are believed to be vitreous mixtures of Ga2O3+P2O5. Films grown with anodic bias exhibited a deficiency of Ga in a ~200 Å region at the GaP-oxide interface. 相似文献
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Using a nuclear reaction, the polarized short-lived -emitters12B and12N were implanted into Si, Ge, and GaP crystals. Hyperfine fields were studied via both NMR techniques and an external magnetic holding field Hext on-off techniques in an Hext range 0–8 kG and a temperature range 100–1000 K. No significant NMR signal was observed between 2 and 30 MHz for12N in Si and Ge despite maintenance of 60% polarization at T100 K and Hext>4 kG, whereas for12B in Si at T>800 K almost full polarization was found at the Larmor frequency. 相似文献
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Optically detected magnetic resonance (ODMR) of bismuth and sulphur impurities in GaP is reported. The results are compared to previous measurements by Cavenett et al. on GaP:N and further confirm the model proposed by these authors to explain the observed decrease in photoluminescence. 相似文献
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Results of experimental and theoretical investigations into the conversion of the phase modulation of light into its intensity modulation in photorefractive crystals are presented. Based on the vector diffraction theory, an analytical expression describing a phase demodulation in crystals in an external electric field applied in an arbitrary direction is derived. The phase demodulation is used to determine the space-charge field amplitude in cubic crystals. It is demonstrated that the space-charge magnitude measured in GaP and Bi12TiO20 crystals is less than that predicted by the Kukhtarev single-level model. 相似文献
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Atomic structures of N-related hydrogen complexes in GaP:N are calculated from first principles. As the more electronegative N bonds H stronger than P, it stabilizes the H(2)(*) complex that is otherwise unstable against the formation of an H2 molecule. This provides the first theoretical proof that H(2)(*) can be stable in a III-V semiconductor. The previously proposed H-N-H dihydride model is found to be unstable against spontaneously transforming into H(2)(*), which involves only monohydrides, H-N and H-Ga. The calculated local vibrational frequencies and isotope shifts are in good agreement with experiment. 相似文献