Analytical study of effect of energy band parameters and lattice temperature on conduction band offset in AlN/Ga2O3 HEMT

Apart from other factors, band alignment led conduction band offset (CBO) largely affects the two dimensional electron gas (2DEG) density ns in wide bandgap semiconductor based high electron mobility transistors (HEMTs). In the context of assessing various performance metrics of HEMTs, rational estimation of CBO and maximum achievable 2DEG density is critical. Here, we present an analytical study on the effect of different energy band parameters-energy bandgap and electron affinity of heterostructure constituents, and lattice temperature on CBO and estimated 2DEG density in quantum triangular-well. It is found that at thermal equilibrium, ns increases linearly with ?EC at a fixed Schottky barrier potential, but decreases linearly with increasing gate-metal work function even at fixed ?EC, due to increased Schottky barrier heights. Furthermore, it is also observed that poor thermal conductivity led to higher lattice temperature which results in lower energy bandgap, and hence affects ?EC and ns at higher output currents.

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Impact of Interface Defect Passivation on Conduction Band Offset at SiO2/4H-SiC Interface

Materials Science Forum ◽

10.4028/www.scientific.net/msf.717-720.721 ◽

2012 ◽

Vol 717-720 ◽

pp. 721-724 ◽

Cited By ~ 5

Author(s):

Takuji Hosoi ◽

Takashi Kirino ◽

Atthawut Chanthaphan ◽

Yusuke Uenishi ◽

Daisuke Ikeguchi ◽

...

Keyword(s):

Conduction Band ◽

Photoelectron Spectroscopy ◽

Hydrogen Gas ◽

Band Alignment ◽

Band Offset ◽

Partial Recovery ◽

Conduction Band Offset ◽

Interface Defect ◽

Defect Passivation ◽

Thermally Grown

The change in energy band alignment of thermally grown SiO2/4H-SiC(0001) structures due to an interface defect passivation treatment was investigated by means of synchrotron radiation photoelectron spectroscopy (SR-PES) and electrical characterization. Although both negative fixed charge and interface state density in SiO2/SiC structures were effectively reduced by high-temparature hydrogen gas annealing (FGA), the conduction band offset (ΔEc) at the SiO2/SiC interface was found to be decreased by about 0.1 eV after FGA. In addition, a subsequent vacuum annealing to induce hydrogen desorption from the interface resulted in not only a slight degradation in interface property but also a partial recovery of ΔEc value. These results indicate that the hydrogen passivation of negatively charged defects near the thermally grown SiO2/SiC interface causes the reduction in conduction band offset. Therefore, the tradeoff between interface quality and conduction band offset for thermally grown SiO2/SiC MOS structure needs to be considered for developing SiC MOS devices.

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Band Alignment of CdS/Cu2ZnSnSe4 Heterointerface and Solar Cell Performances

MRS Advances ◽

10.1557/adv.2017.315 ◽

2017 ◽

Vol 2 (53) ◽

pp. 3157-3162 ◽

Cited By ~ 1

Author(s):

Takehiko Nagai ◽

Shinho Kim ◽

Hitoshi Tampo ◽

Kang Min Kim ◽

Hajime Shibata ◽

...

Keyword(s):

Conduction Band ◽

Band Alignment ◽

Photoemission Spectroscopy ◽

Band Offset ◽

Valence Band Offset ◽

X Ray ◽

Heterojunction Solar Cells ◽

Conduction Band Offset ◽

Ultraviolet Photoemission Spectroscopy ◽

Large Spike

ABSTRACTWe determined that the conduction band offset (CBO) and the valence band offset (VBO) at the CdS/ Cu2ZnSnSe4 (CZTSe) heterointerface are +0.56 and +0.89eV, respectively, by using X-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and inversed photoemission spectroscopy (IPES). A positive CBO value, so-called “spike” structure, means that the position of conduction band becomes higher than that of absorber layer. The evaluated CBO of +0.56 eV suggests that the conduction band alignment at CdS/CZTSe interface is enough to become an electron barrier. Despite such a large spike structure in the conduction band at the interface, a conversion efficiency of 8.7 % could be obtained for the CdS/CZTSe heterojunction solar cells.

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Chemical Composition and Electronic Properties of CuInS2/Zn(S,O) Interfaces

MRS Proceedings ◽

10.1557/proc-1165-m03-07 ◽

2009 ◽

Vol 1165 ◽

Cited By ~ 2

Author(s):

Rodrigo Sáez-Araoz ◽

Iver Lauermann ◽

Axel Neisser ◽

Martha Ch Lux-Steiner ◽

Ahmed Ennaoui

Keyword(s):

Chemical Composition ◽

Band Gap ◽

Conduction Band ◽

Photoelectron Spectroscopy ◽

Energy Band ◽

Band Offset ◽

Energy Band Gap ◽

Valence Band Offset ◽

X Ray ◽

Conduction Band Offset

AbstractWe report on the chemical deposition and electronic properties of CuInS2/Zn(S,O) interfaces. The Zn(S,O) buffer was grown by a new chemical bath deposition (CBD) process that allows the tailoring of the S/O ratio in the films. Resulting Zn(S,O) films exhibit transparencies above 80% (for λ>390 nm) and an optical energy band gap of 3.9 eV which decreases to 3.6 eV after annealing in air at 200°C. Production line CuInS2 (CIS) absorbers provided by Sulfurcell Solartechnik GmbH are used as substrates for the investigation of the CIS/Zn(S,O) interface and the chemical composition of Zn(S,O). A ZnS/(ZnS+ZnO) ratio of 0.5 is found by X-ray photoelectron spectroscopy and X-ray excited Auger electron spectroscopy (XPS and XAES). The valence band offset between the heterojunction partners (ΔEV = 1.8 ± 0.2 eV) has been determined by means of XPS and ultraviolet photoelectron spectroscopy (UPS). Considering the energy band gap of the CIS absorber and the measured band gap of Zn(S,O), the conduction band offset (ΔEC) is calculated as: resulting in a spike of 0.5±0.3 eV in the conduction band at the heterojunction before annealing. After the heat treatment, the valence band offset is reduced to 1.5±0.2 eV and the calculated conduction band offset remains at 0.5±0.3 eV.

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Effects of Post-Deposition Annealing Temperature on Band Alignment and Electrical Characteristics of Lanthanum Cerium Oxide on 4H-SiC

MRS Proceedings ◽

10.1557/opl.2012.1144 ◽

2012 ◽

Vol 1433 ◽

Cited By ~ 5

Author(s):

Way F. Lim ◽

Kuan Y. Cheong

Keyword(s):

Conduction Band ◽

Annealing Temperature ◽

Band Alignment ◽

Trap Density ◽

Band Offset ◽

Interface Trap Density ◽

Interface Trap ◽

Post Deposition Annealing ◽

Conduction Band Offset ◽

Post Deposition

ABSTRACTInvestigation of lanthanum cerium oxide as a gate oxide on 4H-SiC was performed by varying post-deposition annealing temperature from 400 to 1000°C. Energy band alignment and band gap of bulk oxide and interfacial layer (IL) with respect to SiC were extracted using X-ray photoelectron microscopy. Two band alignment structures were proposed and the change of band alignment was affected by the changes in chemical composition in bulk oxide and in IL that may induce lattice strains and dipoles. A conduction band offset of IL/SiC was 0.97 eV for sample annealed at 1000°C, which was comparable to the value extracted from Fowler-Nordheim model. The acquisition of sufficient conduction band offset, coupled with the lowest slow trap density, effective oxide charges, interface trap density, as well as total interface trap density, yielded the lowest leakage current density for this sample.

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Conduction Band Offset Effect on the Cu2ZnSnS4 Solar Cells Performance

Annales de Chimie Science des Matériaux ◽

10.18280/acsm.450601 ◽

2021 ◽

Vol 45 (6) ◽

pp. 431-437

Author(s):

Ahmed Redha Latrous ◽

Ramdane Mahamdi ◽

Naima Touafek ◽

Marcel Pasquinelli

Keyword(s):

Solar Cells ◽

Conduction Band ◽

Power Conversion ◽

Electron Work Function ◽

Band Alignment ◽

Metal Contact ◽

Band Offset ◽

Conduction Band Offset ◽

Optimal Value ◽

Offset Effect

Among the causes of the degradation of the performance of kesterite-based solar cells is the wrong choice of the n-type buffer layer which has direct repercussions on the unfavorable band alignment, the conduction band offset (CBO) at the interface of the absorber/buffer junction which is one of the major causes of lower VOC. In this work, the effect of CBO at the interface of the junction (CZTS/Cd(1-x)ZnxS) as a function of the x composition of Zn with respect to (Zn+Cd) is studied using the SCAPS-1D simulator package. The obtained results show that the performance of the solar cells reaches a maximum values (Jsc = 13.9 mA/cm2, Voc = 0.757 V, FF = 65.6%, ɳ = 6.9%) for an optimal value of CBO = -0.2 eV and Zn proportion of the buffer x = 0.4 (Cd0.6Zn0.4S). The CZTS solar cells parameters are affected by the thickness and the concentration of acceptor carriers. The best performances are obtained for CZTS absorber layer, thichness (d = 2.5 µm) and (ND = 1016 cm-3). The obtained results of optimizing the electron work function of the back metal contact exhibited an optimum value at 5.7 eV with power conversion efficiency of 13.1%, Voc of 0.961 mV, FF of 67.3% and Jsc of 20.2 mA/cm2.

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