Studies of Surface State Densities of Semiconductors by Room-Temperature Photoreflectance

1999 ◽  
Vol 573 ◽  
Author(s):  
J. S. Hwan ◽  
G. S. Chang
Keyword(s):  
Fermi Level ◽  
Barrier Height ◽  
Surface State ◽  
Transport Theory ◽  
Thermionic Emission ◽  
State Density ◽  
Surface Barrier ◽  
Novel Approach ◽  
State Densities ◽  
Surface Fermi Level

ABSTRACTIn this study, we develop a novel approach to determine the surface Fermi level and the surface state densities of semiconductors. The built-in electric field and thus the surface barrier height are evaluated from the Franz-Keldysh oscillations in the PR spectra. Based on the thermionic-emission theory and current-transport theory, the surface state density as well as the pinning position of the surface Fermi level can be determined from the dependence of the surface barrier height on the pump beam intensity. Even though this method is significantly simpler, easier to perform, and time efficient compared with other approaches, the results obtained agree with the literature.

Strong surface Fermi level pinning and surface state density in GaAs0.65Sb0.35 surface intrinsic-n+ structure

2009 ◽  
Vol 95 (14) ◽  
pp. 141914 ◽  
Author(s):  
K. I. Lin ◽  
H. C. Lin ◽  
J. T. Tsai ◽  
C. S. Cheng ◽  
Y. T. Lu ◽  
...  
Keyword(s):  
Fermi Level ◽  
Surface State ◽  
State Density ◽  
Surface State Density ◽  
Fermi Level Pinning ◽  
Strong Surface ◽  
Surface Fermi Level

Determination of surface barrier height and surface state density in GaN films grown on sapphire substrates

2004 ◽  
Vol 831 ◽  
Author(s):  
Seong-Eun Park ◽  
Joseph J. Kopanski ◽  
Youn-Seon Kang ◽  
Lawrence H. Robins ◽  
Hyun-Keel Shin
Keyword(s):  
Barrier Height ◽  
Surface State ◽  
Deep Level ◽  
Surface States ◽  
State Density ◽  
Beam Power ◽  
Surface Barrier ◽  
Surface State Density ◽  
Sapphire Substrates ◽  
Surface Electric Field

ABSTRACTPhotoreflectance (PR) modulation spectroscopy was performed to investigate surface properties of GaN films grown on sapphire substrates. From the period of the Franz-Keldysh oscillations, the surface electric field across the GaN space charge region was found to be (197 ± 11) kV/cm, which corresponds to a surface state density of 1.0×1012 cm−2. A surface barrier height of 0.71 eV was determined by fitting the dependence of the PR intensities on pump beam power density. We suggest that a deep level is formed at 2.68 eV above the GaN valence band edge due to the large density of surface states.

GaAsSb bandgap, surface fermi level, and surface state density studied by photoreflectance modulation spectroscopy

2012 ◽  
Vol 100 (22) ◽  
pp. 222104 ◽  
Author(s):  
J. S. Hwang ◽  
J. T. Tsai ◽  
I. C. Su ◽  
H. C. Lin ◽  
Y. T. Lu ◽  
...  
Keyword(s):  
Fermi Level ◽  
Surface State ◽  
State Density ◽  
Modulation Spectroscopy ◽  
Surface State Density ◽  
Surface Fermi Level

Passivation of Surface and Bulk Defects in InP

1992 ◽  
Vol 262 ◽  
Author(s):  
Sathya Balasubramanian ◽  
Vikram Kumar ◽  
N. Balasubramanian ◽  
V. Premachandran
Keyword(s):  
Fermi Level ◽  
Plasma Treatment ◽  
Band Gap ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Depth Profile ◽  
Hydrogen Plasma ◽  
Deep Levels ◽  
Fermi Level Position ◽  
Surface Fermi Level

ABSTRACTThe effect of sulfur and hydrogen plasma treatment on the Schottky barrier and photoluminescence (PL) properties of p-InP is reported. Both the treatments increase the barrier height of Au/p-InP diodes and band to band PL. This is explained as being due to a shift in the surface fermi level position towards the P vacancy related pinning level in the top half of the band gap. The H+ treatment passivates the shallow and deep levels as observed from the C-V depth profile and PL respectively.

Novel Oxides for Passivating AlGaN/GaN HEMT and Providing Low Surface State Densities at Oxide/GaN Interface

2003 ◽  
Vol 764 ◽  
Author(s):  
F. Ren ◽  
B. Luo ◽  
J. Kim ◽  
R. Mehandru ◽  
B. P. Gila ◽  
...  
Keyword(s):  
Surface State ◽  
Communication Systems ◽  
Surface Passivation ◽  
Surface States ◽  
Interface State ◽  
High Energy ◽  
State Density ◽  
Oxide Semiconductor ◽  
High Electron ◽  
State Densities

Both MgO and Sc2O3 are shown to provide low interface state densities (in the 1011 eV-1 cm-2 range) on n- and p-GaN, making them useful for surface passivation layers to mitigate current collapse in GaN/AlGaN high electron mobility transistors(HEMTs) and also gate dielectrics for metal-oxide semiconductor(MOS) devices. Clear evidence of inversion has been demonstrated in gate-controlled MOS p-GaN diodes using both types of oxide. Charge pumping measurements on diodes undergoing a high temperature implant activation anneal show a total surface state density of ∼3 × 1012 cm-2. On HEMT structures, both oxides provide effective passivation of surface states and these devices show improved output power. The MgO/GaN diodes and Sc2O3 passivated HEMT are also found to be quite radiation-resistant, making them attractive for satellite and terrestrial communication systems requiring a high tolerance to high energy(40MeV) protons.

scholarly journals Fermi-level pinning in methylammonium lead iodide perovskites

Nanoscale ◽  
2019 ◽  
Vol 11 (36) ◽  
pp. 16828-16836 ◽  
Author(s):  
Thibaut Gallet ◽  
David Grabowski ◽  
Thomas Kirchartz ◽  
Alex Redinger
Keyword(s):  
Fermi Level ◽  
Surface State ◽  
State Density ◽  
Scanning Tunnelling Microscopy ◽  
Lead Iodide ◽  
Surface State Density ◽  
Fermi Level Pinning ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Methylammonium Lead Iodide

Scanning tunnelling microscopy measurements reveal grain dependent changes in surface state density and workfunctions on polycrystalline CH3NH3PbI3 absorbers.

Temperature Dependent Schottky Contacts to InP and GaAs

1991 ◽  
Vol 240 ◽  
Author(s):  
Z. Q. Shi ◽  
R. L. Wallace ◽  
W. A. Anderson
Keyword(s):  
Substrate Temperature ◽  
Fermi Level ◽  
Barrier Height ◽  
Leakage Current ◽  
Deep Level ◽  
Interface State ◽  
State Density ◽  
Fermi Level Pinning ◽  
Order Of Magnitude ◽  
Transient Spectroscopy

ABSTRACTThe barrier height of a Pd/n-InP diode was found to be increased from 0.48 to 0.96eV with the substrate temperature decreased from 300 to 77K during metal deposition. The leakage current density was reduced by more than six order of magnitude. It is obvious that the interface Fermi-level position lies well outside the variance associated with Fermi-level pinning. The barrier height for the Au/n-GaAs diode was found to be increased by about 0.25 eV with low temperature deposition and the leakage current reduced by more than five orders of magnitude. The mechanism responsible for the ultrahigh barrier height obtained at low substrate temperature was investigated by Raman spectroscopy, current voltage temperature measurement, deep level transient spectroscopy, and electroreflectance technique. The metal-insulator-semiconductor (MIS)-like structure formed at low substrate temperature and the reduction of interface state density may be the main reason for the dramatic enhancement of Schottky barrier height.

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