Topic
Band offset
About: Band offset is a research topic. Over the lifetime, 2446 publications have been published within this topic receiving 53450 citations.
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TL;DR: In this paper, the authors used photoluminescence excitation measurements to determine the band offset ratios for GalnP/GaAs and AlInP/GAAs quantum wells grown by gas-source molecular beam epitaxy.
Abstract: We report the determination of band offset ratios, using photoluminescence excitation measurements, for GaInP/GaAs and AlInP/GaAs quantum wells grown by gas-source molecular beam epitaxy. To reduce the uncertainty related to the intermixing layer at heterointerfaces, the residual group-V source evacuation time was optimized for abrupt GalnP/GaAs (AlInP/GaAs) interfaces. Based upon thickness and composition values determined by double-crystal x-ray diffraction simulation and cross-sectional transmission electron microscopy, the transition energies of GalnP/GaAs and AlInP/GaAs quantum wells were calculated using a three-band Kane model with varying band-offset ratios. The best fit of measured data to calculated transition energies suggests that the valence-band offset ratio (γ band discontinuity) was 0.63 ± 0.05 for GalnP/GaAs and 0.54 ± 0.05 for AlInP/GaAs heterostructures. This result showed good agreement with photoluminescence data, indicating that the value is independent of temperature.
16 citations
TL;DR: In this article, the photoconductivity and Hall effect in Ga-doped ZnSe were measured and it was shown that the photocarriers are trapped at the interface, causing an enhancement of the annealing temperature to Ta≈350K.
Abstract: Measurements of the photoconductivity and Hall effect in Ga-doped ZnSe indicate that Ga donors form DX states in ZnSe. When the photocarriers remain in the ZnSe:Ga layer, the photoconductivity is persistent up to Ta= 100K, due to a barrier to recapture the photocarriers, Ec ≈ 0.3eV. Under certain growth conditions, there is a large conduction band offset at the heterojunction with the GaAs substrate. The photocarriers are trapped at the interface, causing an enhancement of the annealing temperature to Ta≈350K. We discuss the implications of these results to device applications.
16 citations
TL;DR: In this paper, Ni was slightly doped into CZTS to change the band offset at the Cu2(Zn,Ni)SnS4 (CZNTS)/CdS interface.
Abstract: Knowledge of band-gap engineering and band-alignment matching at the Cu2ZnSnS4 (CZTS)/CdS interface are important for high-efficiency CZTS thin film solar cells. A negative conduction band offset (CBO) is usually obtained at the CZTS/CdS interface, forming a cliff interface and recombination center that reduces the photocurrent. We report a new attempt in which Ni was slightly doped into CZTS to change the band offset at the Cu2(Zn,Ni)SnS4 (CZNTS)/CdS interface (, ). Experimental results showed that the band gap of the CZNTS absorber was strongly associated with the Ni composition, changing from 1.43 eV in pure CZTS to a narrow band gap of 1.26 eV in CZNTS (). The valence band offset (VBO) values were −1.25 eV, − 1.20 eV, and −1.12 eV when x was 0, 0.1, and 0.3, respectively. The CBO at the interface varied from negative (−0.28 eV) to positive (0.02 eV) when x was changed from 0 to 0.3. This finding demonstrated that Ni doping is an efficient way to change the CBO from a cliff to a spike, thus is helpful in reducing the interfacial recombination and enhancing the photovoltaic properties.
16 citations
TL;DR: In this paper, the authors used hard X-ray photoelectron spectroscopy for the first time to determine the band diagrams between mixed oxide and GaN for various Si atom fraction x values.
Abstract: An Al1− x Si x O y mixed oxide has been deposited on GaN by plasma-enhanced atomic layer deposition. The band diagrams between the mixed oxide and GaN for various Si atom fraction x values are determined by hard X-ray photoelectron spectroscopy for the first time. The band gap of the mixed oxide increases with increasing x. This dependence has a large bowing parameter of 1.5 eV. We have successfully obtained conduction band offset (ΔE C) and valence band offset (ΔE V) as a function of x: ΔE C (eV) = 1.6 + 0.4x + 1.2x 2 and ΔE V (eV) = 1.7 + 0.34x + 0.36x 2. These relationships enable us to design GaN metal–oxide–semiconductor devices using the Al1− x Si x O y mixed oxide.
16 citations
TL;DR: In this paper, first-principles DFT simulations provide strong evidence that, at zero temperature, for SiGe oriented SiGe nanowires (NWs), the segregated structure is preferable with respect to the mixed ones; for this observation two different schemes of calculations are presented and discussed.
Abstract: Results of first-principles DFT simulations provide strong evidence that, at zero temperature, for [110] oriented SiGe nanowires (NWs), the segregated structure is favoured with respect to the mixed ones; for this observation two different schemes of calculations are presented and discussed. Moreover the segregation strongly influences the NWs electronic properties, inducing a reduced quantum confined effect (RQCE). We show here that it depends on the effect of strain in the plane normal to the direction of growth and not on the choice of lattice parameter in the direction of growth. A qualitative evaluation of the band offset between Si and Ge for SiGe NWs is also presented.
15 citations