Thickness Dependence of Electronic Properties of GaN Epi-layers

1996 ◽  
Vol 449 ◽  
Author(s):  
W. Götz ◽  
J. Walker ◽  
L.T. Romano ◽  
N.M. Johnson ◽  
R.J. Molnar
Keyword(s):  
Hall Effect ◽  
Electronic Properties ◽  
Deep Level ◽  
Variable Temperature ◽  
Hall Effect Measurement ◽  
Interface Layer ◽  
Hydride Vapor Phase Epitaxy ◽  
Conduction Path ◽  
Hall Effect Measurements ◽  
Transient Spectroscopy

ABSTRACTThe electronic properties of heteroepitaxial GaN were investigated for unintentionally doped, n-type films grown by hydride vapor phase epitaxy on sapphire substrates. The GaN layers were characterized by variable temperature Hall-effect measurement, capacitance-voltage (C-V) measurements, and deep level transient spectroscopy (DLTS). The measurements were performed on as-grown, 13 μn thick films and repeated after thinning by mechanical polishing to 7 μm and 1.2 μm. The room temperature electron concentrations as determined by the Hall-effect measurements were found to increase from ∼1017 cm−3 (13 μm) to ∼1020 cm−3 (1.2 μm) with decreasing film thickness. However, the C-V and DLTS measurements revealed that the ionized, effective donor and deep level concentrations, respectively, remained unchanged in regions close to the top surface of the films. These findings are consistent with the presence of a thin, highly conductive near interface layer which acts as a parasitic, parallel conduction path. Possible sources of such a shunt near the GaN/sapphire interface include oxygen contamination from the sapphire substrate or a structurally highly defective, 300 nm thick interface layer.

Shallow and Deep Level Defects in GaN

1995 ◽  
Vol 395 ◽  
Author(s):  
W. Götz ◽  
N.M. Johnson ◽  
D.P. Bour ◽  
C. Chen ◽  
H. Liu ◽  
...  
Keyword(s):  
Deep Level ◽  
Variable Temperature ◽  
Shallow Donor ◽  
Deep Levels ◽  
Electron Photoemission ◽  
Hall Effect Measurements ◽  
Transient Spectroscopy ◽  
P Type ◽  
Capacitance Transient ◽  
Threshold Energies

ABSTRACTShallow and deep electronic defects in MOCVD-grown GaN were characterized by variable temperature Hall effect measurements, deep level transient spectroscopy (DLTS) and photoemission capacitance transient spectroscopy (O-DLTS). Unintentionally and Si-doped, n-type and Mg-doped, p-type GaN films were studied. Si introduces a shallow donor level into the band gap of GaN at ∼Ec - 0.02 eV and was found to be the dominant donor impurity in our unintentionally doped material. Mg is the shallowest acceptor in GaN identified to date with an electronic level at ∼Ev + 0.2 eV. With DLTS deep levels were detected in n-type and p-type GaN and with O-DLTS we demonstrate several deep levels with optical threshold energies for electron photoemission in the range between 0.87 and 1.59 eV in n-type GaN.

Quantitative Investigation of Near Interface Traps in 4H-SiC MOSFETs via Drain Current Deep Level Transient Spectroscopy

2017 ◽  
Vol 897 ◽  
pp. 111-114 ◽  
Author(s):  
Martin Hauck ◽  
Julietta Weisse ◽  
Johannes Lehmeyer ◽  
Gregor Pobegen ◽  
Heiko B. Weber ◽  
...  
Keyword(s):  
Hall Effect ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Drain Current ◽  
Charge Carrier Density ◽  
Interface Traps ◽  
Quantitative Investigation ◽  
Inversion Charge ◽  
Hall Effect Measurements ◽  
Transient Spectroscopy

Drain current DLTS (ID-DLTS) and Hall effect measurements were carried out on two types of 4H-SiC n-MOSFETs, one with a post oxidation annealing (POA) in NO and one in O2 atmosphere. Hall effect measurements show a reduction of Dit by POA in NO compared to POA in O2 and, as a consequence, a higher inversion charge carrier density, while the Hall mobility is only weakly affected by the introduction of nitrogen during POA. Based on ID-DLTS we provide a method for a quantitative and selective investigation of near interface traps (NITs) in the oxide. It is shown that POA in NO strongly reduces the density of NITs.

Electron Irradiation Induced Trap In N-Type Gan

1997 ◽  
Vol 482 ◽  
Author(s):  
Z-Q. Fang ◽  
J. W. Hemsky ◽  
D. C. Look ◽  
M. P. Mack ◽  
R. J. Molnar ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Organic Chemical ◽  
Electric Field Effects ◽  
Metal Organic ◽  
Transient Spectroscopy ◽  
Organic Chemical Vapor Deposition

AbstractA 1-MeV-electron-irradiation (EI) induced trap at Ec-0.18 eV is found in n-type GaN by deep level transient spectroscopy (DLTS) measurements on Schottky barrier diodes, fabricated on both metal-organic-chemical-vapor-deposition and hydride-vapor-phase-epitaxy material grown on sapphire. The 300-K carrier concentrations of the two materials are 2.3 × 1016 cm−3 and 1.3 × 1017 cm−3, respectively. Up to an irradiation dose of 1 × 1015 cm−2, the electron concentrations and pre-existing traps in the GaN layers are not significantly affected, while the EI-induced trap is produced at a rate of at least 0.2 cm−1. The DLTS peaks in the two materials are shifted slightly, possibly due to electric-field effects. Comparison with theory suggests that the defect is most likely associated with the N vacancy or Ga interstitial.

Electronic Properties of ZnO/Si Heterojunction Prepared by ALD.

2011 ◽  
Vol 178-179 ◽  
pp. 130-135 ◽  
Author(s):  
Vincent Quemener ◽  
Mari Alnes ◽  
Lasse Vines ◽  
Ola Nilsen ◽  
Helmer Fjellvåg ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Deep Level ◽  
Atomic Layer ◽  
Substantial Improvement ◽  
Conduction Band Edge ◽  
Energy Position ◽  
Layer Deposition ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Transient Spectroscopy

ZnO/n-Si and ZnO/p-Si heterostructures were prepared by Atomic layer deposition (ALD) and the electronic properties have been investigated by Current-Voltage (I-V), Capacitance-Voltage (C-V) and Deep level transient spectroscopy (DLTS) measurements. DLTS measurements show two dominants electron traps at the interface of the ZnO/n-Si junction with energy position at 0.07 eV and 0.15 eV below the conduction band edge, labelled E(0.07) and E(0.15), respectively, and no electrically active defects at the interface of the ZnO/p-Si junction. E(0.07) is reduced by annealing up to 400°C while E(0.15) is created at 500°C. The best heterostructure is found after heat treatment at 400°C with a substantial improvement of the current rectification for ZnO/n-Si and the formation of Ohmic contact on ZnO/p-Si. A reduction of the interface defects correlates with an improvement of the crystal structure of the ZnO film with a preferred orientation along the c-axis.

scholarly journals Molecular detection by liquid gated Hall effect measurements of graphene

Nanoscale ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 930-935 ◽  
Author(s):  
Hualin Zhan ◽  
Jiri Cervenka ◽  
Steven Prawer ◽  
David J. Garrett
Keyword(s):  
Hall Effect ◽  
Sheet Resistance ◽  
Hall Coefficient ◽  
Molecular Detection ◽  
Hall Effect Measurement ◽  
Effect Measurement ◽  
Hall Effect Measurements

A liquid gated Hall effect measurement of graphene shows that the Hall coefficient is more sensitive to the change of l-histidine concentration in the pM range than the sheet resistance.

scholarly journals Electronic Properties and Density of States of Self-Assembled GaSb/GaAs Quantum Dots

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
T. Nowozin ◽  
A. Wiengarten ◽  
L. Bonato ◽  
D. Bimberg ◽  
Wei-Hsun Lin ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Density Of States ◽  
Deep Level ◽  
Material System ◽  
A Value ◽  
Capacitance Voltage ◽  
Different Temperatures ◽  
Self Assembled ◽  
Transient Spectroscopy ◽  
The Individual

The electronic properties of a self-assembled GaSb/GaAs QD ensemble are determined by capacitance-voltage (C-V) and deep-level transient spectroscopy (DLTS). The charging and discharging bias regions of the QDs are determined for different temperatures. With a value of 335 (±15) meV the localization energy is rather small compared to values previously determined for the same material system. Similarly, a very small apparent capture cross section is measured (1·10−16 cm2). DLTS signal analysis yields an equivalent to the ensemble density of states for the individual energies as well as the density function of the confinement energies of the QDs in the ensemble.

Spectroscopic Identification of the Acceptor-Hydrogen Complex in Mg-Doped GaN Grown by MOCVD

1997 ◽  
Vol 468 ◽  
Author(s):  
W. Götz ◽  
M. D. McCluskey ◽  
N. M. Johnson ◽  
D. P. Bour ◽  
E. E. Haller
Keyword(s):  
Hall Effect ◽  
Absorption Spectra ◽  
Thermal Activation ◽  
Variable Temperature ◽  
Chemical Vapor ◽  
Thermally Activated ◽  
Local Vibrational Mode ◽  
Hall Effect Measurements ◽  
Spectroscopic Identification ◽  
Mg Doped

ABSTRACTMg-doped GaN films grown by metalorganic chemical vapor deposition were characterized by variable-temperature Hall-effect measurements and Fourier-transform infrared absorption spectroscopy. As-grown, thermally activated, and deuterated Mg-doped GaN samples were investigated. The existence of Mg-H complexes in GaN is demonstrated with the observation of a local vibrational mode (LVM) at 3125 cm-1 (8 K). At 300 K this absorption line shifts to 3122 cm-1. The intensity of the LVM line is strongest in absorption spectra of as-grown GaN. Mg which is semi-insulating. Upon thermal activation, the intensity of the LVM line significantly decreases and an acceptor concentration of 2×1019cm-3 is derived from the Hall-effect data. After deuteration at 600°C the resistivity of the Mg-doped GaN increased by four orders of magnitude. A LVM line at 2321 cm-1 (8 K) appears in the absorption spectra which is consistent with the isotopie shift of the vibrational frequency when D is substituted for H.

Electrical and optical investigation of the position of vanadium related defects in the 4H and 6H SiC bandgaps

1996 ◽  
Vol 423 ◽  
Author(s):  
J. R. Jenny ◽  
M. Skowronski ◽  
W. C. Mitchel ◽  
S. R. Smith ◽  
A. O. Evwaraye ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Hall Effect ◽  
Deep Level ◽  
Polarized Light ◽  
Conduction Band Edge ◽  
Optical Investigation ◽  
Admittance Spectroscopy ◽  
Acceptor Level ◽  
Transient Spectroscopy ◽  
Spectroscopy Optical

AbstractHall effect, deep level transient spectroscopy, optical absorption, and optical admittance spectroscopy were employed to determine the position of the vanadium acceptor and vanadiumnitrogen complex in vanadium- and nitrogen-doped 4H and 6H SiC. Hall effect results indicate that the acceptor position in 4H(6H) SiC is 0.80(0.66) eV beneath the conduction band edge. The DLTS signature of the defect in the 4H polytype showed an ionization energy of 806 meV and a capture cross section of 1.8×10−16 cmr−2 The optical absorption measurements proved that the acceptor level investigated is related to isolated vanadium, and therefore the vanadium acceptor level. Based upon DLTS and SIMS measurements, the maximum solubility of vanadium in SiC was determined to the 3×10−17 crn3. An examination of polarized light experiments indicates that vanadium also complexes with another element to form electronic(at 5000 cm−1) and vibrational absorption(at 683 cm−1) bands. While the other constituent cannot be identified, evidence suggests that nitrogen is a likely candidate. This complex introduces a deep level at Ec−0.78 eV as determined using optical admittance spectroscopy.

Effects of Oxygen Partial Pressure on the Properties of SnOx Thin Films Doped with Indium

2021 ◽  
Vol 16 (5) ◽  
pp. 819-826
Author(s):  
Myeong Kyun Lyou ◽  
Hyunki Kim ◽  
SeoGwon Kim ◽  
Byung Seong Bae ◽  
Eui-Jung Yun
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Hall Effect ◽  
Photoelectron Spectroscopy ◽  
Secondary Ion Mass Spectrometry ◽  
Hall Effect Measurement ◽  
Amorphous Structure ◽  
X Ray ◽  
Hall Effect Measurements

This study examined the effects of the oxygen partial pressure on the properties of heavily indium-doped tin-oxide (In-SnOx) thin films grown at room temperature by reactive direct-current pulse sputtering from a mixed metallic target containing Sn (70 atomic %)-In (30 atomic %). X-ray photoelectron spectroscopy (XPS), dynamic secondary-ion mass spectrometry, X-ray diffraction (XRD), and Hall Effect measurements showed that the In-SnOx samples prepared with oxygen pressures of 10–20% had metallic properties. This was attributed to the notable Sn0 area ranges of 5.6–17.3%, low resistivity ranges of 5.5×10−3–2×10−4 Ωcm, and the high carrier concentration ranges of 3.5×1021–5.1×1022/cm3. On the other hand, the Sn4+ area and the resistivity increased significantly to 73.3% and 9.4 Ωcm. In comparison, the Sn2+ area and the electron concentration decreased dramatically to 23.6% and 6.5×1016/cm3, respectively, with increasing oxygen partial pressure up to 30%. The samples prepared with oxygen pressures higher than 20% exhibited nonmetallic properties with the dominant n-type SnO2 phase. This steep increase in the Sn4+ area was attributed to an increase in the oxygen contents in the samples, resulting in a decrease in the number of oxygen vacancy donors in the samples prepared with oxygen pressures higher than 20%. The decrease in the Sn2+ area was related to a decrease in the indium (In) contents in the samples, which also decreased the number of metal acceptors in the samples. XRD also showed that the metallic indium stannide (In0.2Sn0.8) and In–Sn–O(ITO) peaks coexisted for samples prepared with an oxygen pressure of 0–10%. In contrast, the samples prepared with oxygen pressures higher than 20% had an amorphous structure with SnO2 and SnO phases, supporting the XPS and Hall Effect measurement results.

Electrical properties of MBE grown Si-doped AlxGa1−xN as a function of nominal Al mole fraction up to 0.5

2001 ◽  
Vol 680 ◽  
Author(s):  
M. Ahoujja ◽  
Y. K. Yeo ◽  
R. L. Hengehold ◽  
J. E. Van Nostrand
Keyword(s):  
Electrical Properties ◽  
Hall Effect ◽  
Mole Fraction ◽  
Molecular Beam ◽  
Variable Temperature ◽  
Type Region ◽  
Si Doping ◽  
Gas Source ◽  
Hall Effect Measurements ◽  
Si Doped

ABSTRACTHall-effect measurements were conducted on Si-doped AlxGa1−xN films grown on sapphire substrate by gas source molecular beam epitaxy. The Al mole fraction in the 1 [.proportional]m thick AlxGa1−xN was 0.0, 0.3, and 0.5, and the Si doping concentration was kept at a nominal value of 1018 cm−3. Variable temperature Hall-effect measurements reveal a presence of a highly degenerate n-type region at the AlxGa1−xN /sapphire interface. This degenerate interfacial layer dominates the electrical properties below 30 K and significantly affects the properties of the AlxGa1−xN layer. Thus, by using a two-layer conducting model, the carrier concentration and mobility of the AlxGa1−xN layer alone are obtained.

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