Role Of Deep Level Trapping On Surface Photovoltage Of semiinsulating GaAs

1996 ◽  
Vol 426 ◽  
Author(s):  
Qiang Liu ◽  
Harry E. Ruda ◽  
Ivoil P. Koutzarov ◽  
Lech Jedral ◽  
Genmao Chen ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Deep Level ◽  
Surface Region ◽  
Interface State ◽  
Thermal Recovery ◽  
Surface Photovoltage ◽  
Effective Electron ◽  
Near Surface ◽  
Dual Beam ◽  
Bias Pulse

AbstractDual beam (bias and probe) transient Surface Photovoltage (SPV) measurements were made on undoped Semi-Insulating (SI) GaAs over an extended temperature range. Above 270 K, SPV recovery transients following a bias pulse were shown to reflect near surface conductivity changes; these are in turn controlled by surface/interface state thermal emission. Owing to the absence of a strong surface electric field in this material, the emitted carriers are not immediately removed from the near surface region. The recapturing of the emitted carriers is shown to be responsible for non-exponential conductivity and reciprocal-SPV transients. This behavior is considered to be characteristic of relaxation-type semiconductors with near-surface ungated structures. Below 150 K, the photoinduced transition of EL2 from its ground to metastable state EL2& was shown to change the effective electron and hole mobilities and augment the SPV signals immediately following the bias pulse. Thermally induced EL2& recovery above 120 K decreases the SPV signal from its maximum. This decay transient was analyzed and the decay rate fitted to a single exponential. An activation energy of 0.32 eV and a pre-exponential constant of 1. 9× 1012 s−1 were obtained, and attributed to the thermal recovery rate for EL2&.

Defect Levels in the Near-Surface Region of 2.0 MeV 16O+ Ion Implanted n-GaAs.

1989 ◽  
Vol 163 ◽  
Author(s):  
C.C. Tin ◽  
P.A. Barnes ◽  
T.T. Bardin ◽  
J.G. Pronko
Keyword(s):  
Cross Section ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Surface Region ◽  
Conduction Band Edge ◽  
Defect Structures ◽  
Near Surface ◽  
Defect Levels ◽  
Transient Spectroscopy ◽  
Different Doses

AbstractMeV ion implantation in GaAs is known to cause amorphization of the region at the end of the ion range. The near-surface region, however, is still crystalline albeit heavily compensated. We have carried out deep level transient spectroscopy (DLTS) studies of the defect levels in the near—surface region of n—GaAs samples implanted with different doses of 2.0 MeV 16O+ ions.A comparison between the defect structures in the original and the implanted samples shows that implantation produced a broad range of defect levels ranging from 0.58 to 0.3 eV from the conduction band edge. This broad range of defects has an unusually large capture cross—section. The intensities of the DLTS peaks increase with the dose of 160+ ions. The presence of EL2, which was present in the original samples, was not observed in the implanted samples.Results from measurements made on samples that have been implanted at 200°C and on implanted samples subjected to rapid thermal annealing will also be discussed.

Defect Engineering and Atomic Relocation Processes in Impurity-Free Disordered GaAs and AlGaAs

2003 ◽  
Vol 799 ◽  
Author(s):  
P. N. K. Deenapanray ◽  
M. Krispin ◽  
W. E. Meyer ◽  
H. H. Tan ◽  
C. Jagadish ◽  
...  
Keyword(s):  
Deep Level ◽  
Surface Region ◽  
Conduction Band Edge ◽  
Defect Engineering ◽  
Pronounced Increase ◽  
Near Surface ◽  
Disordered Layer ◽  
Transient Spectroscopy ◽  
Dopant Atoms ◽  
P Type

ABSTRACTImpurity-free disordering (IFD) of GaAs and AlxGa1-xAs epitaxial layers using SiOx capping in conjunction with annealing was studied by deep level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements. Three dominant electron traps S1 (EC– 0.23 eV), S2* (EC– 0.53 eV), and S4 (EC– 0.74 eV) are created in disordered n-type GaAs. The electron emission rate of S1 is enhanced in the presence of an externally applied electric field. We propose that S1 is a defect that may involve As-clustering or a complex of arsenic interstitials, Asi, and the arsenic-antisite, AsGa. S2* is shown to be the superposition of two defects, which may be VGa-related. S4 is identified as the defect EL2. Our preliminary results indicate that the same set of defects is created in disordered n-type AlxGa1-xAs, with S1 pinned to the conduction band edge, while S2* and S4 are pinned relative to the Fermi level. In contrast to disordering in n-type GaAs, IFD of p-type GaAs results in the pronounced increase in the free carrier concentration in the near-surface region of the disordered layer. Two electrically active defects HA (EV+ 0.39 eV) and HB2 (EV+ 0.54 eV), which we have attributed to Cu- and Asi/AsGa-related levels, respectively, are also observed in the disordered p-GaAs layers. IFD causes segregation of Zn dopant atoms and Cu towards the surface of IFD samples. This atomic relocation process poses serious limitations regarding the application of IFD to the band gap engineering of doped GaAs-based heterostructures.

Characterization of Defects Created in Silicon Due to Etching in Low-Pressure Plasmas Containing Fluorine and Oxygen

1995 ◽  
Vol 396 ◽  
Author(s):  
I. A. Buyanova ◽  
A. Henry ◽  
B. Monemar ◽  
J. L. Lindström ◽  
A. Lamprecht ◽  
...  
Keyword(s):  
Deep Level ◽  
Surface Region ◽  
Energy Shift ◽  
Low Pressure ◽  
Extended Defects ◽  
Near Surface ◽  
Defect Complexes ◽  
Radiation Induced ◽  
Dlts Spectra

AbstractDefect characterization in n-type silicon after the reactive ion etching (RIE) in low-pressure plasmas containing fluorine and oxygen is performed by using photoluminescence (PL) and deep level transient spectroscopies (DLTS). It is shown that RIE treatment results in the formation of (i) luminescence centers giving rise to the C- and G- excitonic lines and broad emission bands related to radiation-induced defect complexes and extended defects and (ii) several electron traps located at 0.16 eV, 0.26 eV, 0.43 eV and 0.58 eV below the conduction band. The addition of oxygen to the SF6 and CF4 plasma is shown to cause nonuniform stress in the near surface region. This stress is responsible for the experimentally observed splitting of the C- and G-excitonic lines, a low energy shift of the phosphorous bound exciton lines, as well as the splitting of the DLTS spectra. It is shown that the stress field is highly inhomogeneous across the wafer, and is rather related to the RIE-induced extended defects than caused by the reaction layer formed on the Si surface.

Cathodoluminescence Deep Level Spectroscopy of Etched and In-Situ Annealed 6H-SiC

1998 ◽  
Vol 512 ◽  
Author(s):  
A. P. Young ◽  
K. Aptowitz ◽  
L. J. Brillson
Keyword(s):  
Electron Beam ◽  
Deep Level ◽  
Surface Region ◽  
Energy Electron ◽  
Temperature Dependent ◽  
Near Surface ◽  
Electron Beam Excitation ◽  
Beam Excitation ◽  
Variable Energy

ABSTRACTThrough variable-energy electron beam excitation (0.5 keV-2.0 keV), we observe depth dependent differences in the cathodoluminescence spectra of 6H-SiC (0001) Si-terminated surfaces. The etched SiC exhibits three deep level defects in the near-surface region, including a defect peak observed at 0.92 eV, known to be associated with vanadium. In-situ annealing produces a dramatic relative decrease in the luminescence from vanadium impurities near the surface after annealing to 500 °C, and then the subsequent re-emergence of vanadium in the nearsurface regime after annealing to 810 °C. This temperature-dependent redistribution suggests either diffusion or segregation of vanadium from the bulk up toward the near-surface region.

Non-Contact, Wafer-Scale Deep Level Transient Spectroscopy (DLTS) Based on Surface Photovoltage (SPV)

1991 ◽  
Vol 240 ◽  
Author(s):  
Jacek Lagowski ◽  
Andrzej Morawski ◽  
Piotr Edelman
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Thermal Emission ◽  
Deep Level ◽  
Depletion Region ◽  
Capacitive Coupling ◽  
Surface Photovoltage ◽  
Surface Barrier ◽  
Schottky Type ◽  
Transient Spectroscopy ◽  
Non Destructive

ABSTRACTWe present a new version of a deep level transient spectroscopy which is suitable for non-contact, non-destructive determination of deep level defects in semiconductor wafers without preparation of metal-semiconductor diodes or p-n junctions.The method relies on deep level thermal emission measurements by the surface photovoltage (SPV) transient following an optical filling pulse. Non-equilibrium occupation of deep levels is realized within the native surface depletion region by the capture of excess minority carriers. Since the native Schottky-type surface barrier is commonly present on semiconductor surfaces, the approach requires no wafer pre-treatments. Non-contact SPV measurements are realized using a capacitive coupling to the wafer front and the wafer back.The quantitative principles of the SPV-DLTS approach are discussed using experimental data obtained on GaAs.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

The Effects of Ion Implantation on the Surface Features of Inconel 600

1985 ◽  
Vol 43 ◽  
pp. 288-289
Author(s):  
John D. Rubio
Keyword(s):  
Grain Boundary ◽  
Ion Implantation ◽  
Nuclear Power ◽  
Power Plants ◽  
Surface Region ◽  
Selective Dissolution ◽  
Boundary Region ◽  
Near Surface ◽  
Inconel 600 ◽  
Steam Generator Tubing

The degradation of steam generator tubing at nuclear power plants has become an important problem for the electric utilities generating nuclear power. The material used for the tubing, Inconel 600, has been found to be succeptible to intergranular attack (IGA). IGA is the selective dissolution of material along its grain boundaries. The author believes that the sensitivity of Inconel 600 to IGA can be minimized by homogenizing the near-surface region using ion implantation. The collisions between the implanted ions and the atoms in the grain boundary region would displace the atoms and thus effectively smear the grain boundary.To determine the validity of this hypothesis, an Inconel 600 sample was implanted with 100kV N2+ ions to a dose of 1x1016 ions/cm2 and electrolytically etched in a 5% Nital solution at 5V for 20 seconds. The etched sample was then examined using a JEOL JSM25S scanning electron microscope.

Microstructural changes of Aluminum Nitride after laser irradiation and electroless copper deposition

1994 ◽  
Vol 52 ◽  
pp. 636-637
Author(s):  
S. Cao ◽  
A. J. Pedraza ◽  
L. F. Allard
Keyword(s):  
Aluminum Nitride ◽  
Laser Irradiation ◽  
Electroless Deposition ◽  
Thermal Evaporation ◽  
Surface Region ◽  
Near Surface ◽  
Laser Patterning ◽  
Electroless Copper ◽  
Excimer Laser Irradiation ◽  
Laser Effect

Excimer-laser irradiation strongly modifies the near-surface region of aluminum nitride (AIN) substrates. The surface acquires a distinctive metallic appearance and the electrical resistivity of the near-surface region drastically decreases after laser irradiation. These results indicate that Al forms at the surface as a result of the decomposition of the Al (which has been confirmed by XPS). A computer model that incorporates two opposing phenomena, decomposition of the AIN that leaves a metallic Al film on the surface, and thermal evaporation of the Al, demonstrated that saturation of film thickness and, hence, of electrical resistance is reached when the rate of Al evaporation equals the rate of AIN decomposition. In an electroless copper bath, Cu is only deposited in laser-irradiated areas. This laser effect has been designated laser activation for electroless deposition. Laser activation eliminates the need of seeding for nucleating the initial layer of electroless Cu. Thus, AIN metallization can be achieved by laser patterning followed by electroless deposition.

Persistent Photoconductivity And Thermal Recovery Kinetics Of Low Energy Ar + Bombarded GaAs

1991 ◽  
Vol 223 ◽  
Author(s):  
A. Vaseashta ◽  
L. C. Burton
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Thermal Recovery ◽  
Low Energy ◽  
Persistent Photoconductivity ◽  
Transport Parameters ◽  
Excellent Correlation ◽  
Proposed Model ◽  
Transient Spectroscopy ◽  
Kinetics Of

ABSTRACTKinetics of persistent photoconductivity, photoquenching, and thermal and optical recovery observed in low energy Ar+ bombarded on (100) GaAs surfaces have been investigated. Rate and transport equations for these processes were derived and simulated employing transport parameters, trap locations and densities determined by deep level transient spectroscopy. Excellent correlation was obtained between the results of preliminary simulation and the experimentally observed values. The exponential decay of persistent photoconductivity response curve was determined to be due to metastable electron traps with longer lifetime and is consistent with an earlier proposed model.

Annealing Effects at the Near-Surface Region of Gallium Arsenide

1992 ◽  
Vol 105-110 ◽  
pp. 1383-1386 ◽  
Author(s):  
Hugh E. Evans ◽  
D.L. Smith ◽  
P.C. Rice-Evans ◽  
G.A. Gledhill ◽  
A.M. Moore
Keyword(s):  
Gallium Arsenide ◽  
Surface Region ◽  
Near Surface ◽  
Annealing Effects
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