scholarly journals Investigation of dopant centres dominating the conduction process in the bulk of un-doped GaSb

2019 ◽  
Vol 13 (4) ◽  
pp. 315-327
Author(s):  
Megersa Wodajo Shura
Keyword(s):  
Energy Level ◽  
Hall Effect ◽  
Fermi Energy ◽  
Activation Energies ◽  
Acceptor Level ◽  
Level System ◽  
Fermi Energy Level ◽  
Majority Carrier ◽  
Temperature Regimes ◽  
Hall Effect Measurements

Abstract In this paper, first, the theoretical description of the effects of the dopant densities and the activation energies on the ionization densities, the chemical potentials corresponding to each dopant levels, the majority carrier densities and the Fermi-energy levels in one-acceptor-level system, highly compensated system and two-acceptor-level system are described in detail. Upon fitting the theoretical to the experimental results obtained by the temperature-dependent Hall effect measurements for three samples of un-doped GaSb, the dopant densities and the activation energies for a system with different dopants are investigated. The obtained results revealed that the dopant activation energy has less (no) effect on the Fermi-energy level and the majority carrier density in the highest temperature regimes. The doping density has also less (no) effect on the Fermi-energy level in the lowest temperature regimes. Finally, fitting of the theoretical to the experimental Hall effect measurements results confirmed the presence of three acceptor and one donor levels dominating the majority carrier densities at different temperature regions in all the samples of un-doped GaSb semiconductor.

Intersubband Transitions in In0.07Ga0.93As/Al0.4Ga0.6As Multiple Quantum Wells

1994 ◽  
Vol 299 ◽  
Author(s):  
F. Szmulowicz ◽  
M. O. Manasreh ◽  
C. Kutsche ◽  
C. E. Stutz
Keyword(s):  
Energy Level ◽  
Quantum Well ◽  
Quantum Wells ◽  
Excited States ◽  
Fermi Energy ◽  
Multiple Quantum Well ◽  
Energy Separation ◽  
Multiple Quantum ◽  
Fermi Energy Level ◽  
Intersubband Transitions

AbstractIntersubband transitions in a series of well-doped ([Si] = 2.0×1018cm−3) In0.07Ga0.93As/Al0.4Ga0.6As multiple quantum well samples were studied as a function of the well width by using the optical absorption technique. A single intersubband transition is observed in samples in which the Fermi energy level is between the ground and the first excited states in the quantum well. On the other hand, two intersubband transitions were recorded in samples where the Fermi energy level lies between the first and the second excited states. These two intersubband transitions were attributed to ground-to-first excited states and first-to-second excited states transitions. The energy separation between the latter two intersubband transitions was found to increase as the well width is increased. The fact that two intersubband transitions were observed in certain samples may suggest that specially designed quantum wells can be used for two color long wavelength infrared detectors.

Graphene-based dual-band independently tunable infrared absorber

Nanoscale ◽  
2018 ◽  
Vol 10 (33) ◽  
pp. 15564-15570 ◽  
Author(s):  
Peng Sun ◽  
Chenglong You ◽  
Amirreza Mahigir ◽  
Tongtong Liu ◽  
Feng Xia ◽  
...  
Keyword(s):  
Energy Level ◽  
Resonant Frequency ◽  
Fermi Energy ◽  
Dual Band ◽  
Fermi Energy Level ◽  
P Absorption

Absorption peaks can independently tune each resonant frequency by only changing the Fermi energy level of one.

Studies on the Interface of TiN/n-GaAs

1994 ◽  
Vol 337 ◽  
Author(s):  
Ho Jie ◽  
Jin Gaolong ◽  
Lu Liwu ◽  
Xu Zhenjia ◽  
Zhang Lichun
Keyword(s):  
Energy Level ◽  
Hall Effect ◽  
Refractory Metal ◽  
Schottky Contacts ◽  
Electrical Performance ◽  
Metal Nitrides ◽  
Donor Level ◽  
Acceptor Level ◽  
Type Layer

ABSTRACTRecent reports on refractory metal nitrides/n-GaAs Schottky contacts have demonstrated that improved electrical performance can be obtained after annealing at temperature between 750 and 850°C . It is thought that a p+-type layer should be responsible for this phenomenon, which may be generated by N or N related defects. In this paper, the role of nitrogen in SI-GaAs and n-GaAs has been investigated by Hall effect and DLTS measurements. No evidence of the formation of a p+-type layer has been observed. A deep energy level of Ec-0.36eV which is thought to be related to N and an enhanced effect of N on the density of EL2 level were observed. DLTS and SIMS techniques were used to study the interface of TiN/n-GaAs Schottky contacts. The Ti3+(3d1)/Ti2+(3d2) single acceptor level at Ec-0.21 eV was observed, but the EL2 donor level is dominant. Combining the experimental results, a discussion is made about the reasons for the improvements of electrical performance after annealing.

scholarly journals A Broadband Tunable Terahertz Metamaterial Absorber Based on Single-Layer Complementary Gammadion-Shaped Graphene

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 860 ◽  
Author(s):  
Fu Chen ◽  
Yongzhi Cheng ◽  
Hui Luo
Keyword(s):  
Energy Level ◽  
Graphene Sheet ◽  
Fermi Energy ◽  
Single Layer ◽  
Dielectric Substrate ◽  
Transverse Magnetic ◽  
Metamaterial Absorber ◽  
Absorption Capacity ◽  
Fermi Energy Level ◽  
Broadband Absorption

We present a simple design of a broadband tunable metamaterial absorber (MMA) in the terahertz (THz) region, which consists of a single layer complementary gammadion-shaped (CGS) graphene sheet and a polydimethylsiloxane (PDMS) dielectric substrate placed on a continuous metal film. The Fermi energy level (Ef) of the graphene can be modulated dynamically by the applied DC bias voltage, which enables us to electrically control the absorption performance of the proposed MMA flexibly. When Ef = 0.8 eV, the relative bandwidth of the proposed MMA, which represents the frequency region of absorption beyond 90%, can reaches its maximal value of 72.1%. Simulated electric field distributions reveal that the broadband absorption mainly originates from the excitation of surface plasmon polaritons (SPPs) on the CGS graphene sheet. Furthermore, the proposed MMA is polarization-insensitive and has wide angles for both transverse-electric (TE) and transverse-magnetic (TM) waves in the broadband frequency range. The broadband absorption capacity of the designed MMA can be effectively adjusted by varying the Fermi energy level of graphene. Lastly, the absorbance of the MMA can be adjusted from 42% to 99.1% by changing the Ef from 0 eV to 0.8 eV, which is in agreement with the theoretical calculation by using the interference 41theory. Due to its simple structure and flexible tunability, the proposed MMA has potential application prospects in tunable filtering, modulators, sensing, and other multispectral devices.

scholarly journals The effect of elastic strains on the adsorption energy of H, O, and OH in transition metals

2021 ◽  
Vol 23 (37) ◽  
pp. 21295-21306
Author(s):  
Carmen Martínez-Alonso ◽  
José Manuel Guevara-Vela ◽  
Javier LLorca
Keyword(s):  
Transition Metals ◽  
Energy Level ◽  
Adsorption Energy ◽  
Fermi Energy ◽  
Fermi Energy Level ◽  
General Law ◽  
Adsorption Energies ◽  
Elastic Strains

The adsorption energies of H, O, and OH on 11 transition metals were calculated as a function of strain. They were related to the Fermi energy level which only depended on the change of the area of the hole due to strain following a general law.

scholarly journals First-Principles Study of Vacancy and Impurities Defects in Graphene

2021 ◽  
Vol 2 (01) ◽  
pp. 93-102
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Energy Level ◽  
Density Of States ◽  
Fermi Energy ◽  
First Principles ◽  
Density Functional ◽  
Partial Density ◽  
Fermi Energy Level ◽  
Vacancy Defects ◽  
Impurity Defects

In this work, we have studied the electronic and magnetic properties of 1C atom vacancy defects in graphene (1Cv-d-G), 1N atom impurity defects in graphene (1NI-d-G) and 1O atom impurity defects in graphene (1OI-d-G) materials through first principles calculations based on spin-polarized density functional theory (DFT) method, using computational tool Quantum ESPRESSO (QE) code. From band structure and density of states (DOS) calculations, we found that supercell structure of monolayer graphene is a zero bandgap material. But, electronic bands of 1Cv-d-G, 1NI-d-G and 1OI-d-G materials split around the Fermi energy level and DOS of up & down spins states appear in the Fermi energy level. Thus, 1Cv-d-G, 1NI-d-G and 1OI-d-G materials have metallic properties. We have studied the magnetic properties of pure and defected materials by analyzing density of states (DOS) and partial density of states (PDOS) calculations. We found that graphene and 1OI-d-G materials have non-magnetic properties. On the other hand, 1C vacancy atom and 1N impurity atom induced magnetization in 1Cv-d-G & 1NI-d-G materials by the rebonding of dangling bonds and acquiring significant magnetic moments of values -0.75μB/cell & 0.05μB/cell respectively through remaining unsaturated dangling bond. Therefore, non-magnetic graphene changes to magnetic 1Cv-d-G and 1NI-d-G materials due to 1C atom vacancy defects and 1N atom impurity defects. The 2p orbital of carbon atoms has main contribution of magnetic moment in these defected structures.

Sign in / Sign up

Export Citation Format

Share Document