Pulsed Co2 Laser Induced Melting and Nonlinear Optical Studies of GaAs

1985 ◽  
Vol 51 ◽  
Author(s):  
R. B. James ◽  
W. H. Christie ◽  
B. E. Mills ◽  
H. L. Burcham
Keyword(s):  
Surface Region ◽  
Auger Spectroscopy ◽  
Optical Studies ◽  
Molten Layer ◽  
Near Surface ◽  
Pulsed Co2 Laser ◽  
Level Model ◽  
Ripple Patterns ◽  
P Type ◽  
Two Level Model

ABSTRACTWe report new optical and structural properties of p-type GaAs that result from the absorption of high-intensity 10.6 μm radiation. Prior to the onset of surface melting, we find that the absorption coefficient decreases with increasing intensity in a manner predicted by an inhomogeneously broadened two-level model. As the energy density of the CO2 laser radiation is increased further, the surface topography shows signs of melting, formation of ripple patterns, and vaporization. Auger spectroscopy and electron-induced x-ray emission show that there is loss of As, compared to Ga, caused by the melting of the surface. Using plain-view TEM we find that Ga-rich islands are formed near the surface during the rapid solidification of the molten layer. Auger and SIMS measurements are used to study the incorporation of oxygen in the near-surface region, and the results show that oxygen incorporation can occur for GaAs samples that have been irradiated in air.

Defects Introduced by Plasma Processing of Silicon

1992 ◽  
Vol 262 ◽  
Author(s):  
J. L. Benton
Keyword(s):  
Bulk Material ◽  
Surface Region ◽  
Surface Damage ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Interstitial Defect ◽  
Comprehensive Picture ◽  
Reaction Region ◽  
Defect Reactions ◽  
P Type

ABSTRACTThe electrical and optical properties of defects introduced by Reactive Ion Etching (RIE) in the near surface region of Si after dry etching with various gases and plasma conditions is studied with spreading Resistance (SR), photoluminescence (PL), and capacitance-voltage profiling (C-V). Plasma etching in chlorine and fluorine based gases produce donors at the surface in both n-type and p-type, Czochralski and float-zone silicon. Isochronal annealing reveals the presence of two distinct regions of dopant compensation. The surface damage region is confined to 1000 Å and survives heat treatment at 400°C, while the defect reaction region extends ≥ 1 μm in depth and recovers by 250°C. A comprehensive picture of the interstitial defect reactions in RIE silicon is completed. The interstitial defects, Ci and Bi, created in the ion damaged near surface region, undergo recombination enhanced diffusion caused by the presence of ultraviolet light in the plasma, resulting in the long range diffusion into the Si bulk. Subsequently, the interstitial atoms are trapped by the background impurities forming the defect pairs, CiOi, CSCi, or BiOi, which are observed experimentally. The depth of the diffusion-limited trapping and the probability of forming specific pairs depends on the relative concentrations of the reactants, oxygen, carbon or boron, present in the bulk material.

Effect of c-Si1-xGex Thickness Grown by LPCVD on the Performance of Thin-Film a-Si/c-Si1-xGex/c-Si Heterojunction Solar Cells

2012 ◽  
Vol 1447 ◽  
Author(s):  
Sabina Abdul Hadi ◽  
Pouya Hashemi ◽  
Nicole DiLello ◽  
Ammar Nayfeh ◽  
Judy L. Hoyt
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Layer Thickness ◽  
Surface Region ◽  
Absorber Layer ◽  
Buffer Layers ◽  
Optical Carrier ◽  
Near Surface ◽  
Heterojunction Solar Cells ◽  
P Type

ABSTRACTIn this paper the effect of Si1-xGex absorber layer thickness on thin film a-Si:H/crystalline-Si1-xGex/c-Si heterojunction solar cells (HIT cells) is studied by simulation and experiment. Cells with 1, 2 and 4 μm-thick epitaxial cap layers of p-type Si0.59Ge0.41 on top of 5 μm Si1-xGex graded buffer layers are fabricated and compared to study the effect of the absorber layer thickness. The results show no change in Voc (0.41V) and that Jsc increases from 17.2 to 18.1 mA/cm2 when the Si0.59Ge0.41 absorber layer thickness is increased from 1 to 4 μm. The effect of thickness on Jsc is also observed for 2 and 4 μm-thick Si and Si0.75Ge0.25 absorber layers. Experiments and simulations show that larger Ge fractions result in a higher magnitude and smaller thickness dependence of Jsc, due to the larger absorption coefficient that increases optical carrier generation in the near surface region for larger Ge contents.

Effect of N2 Plasma Treatments on Dry Etch Damage in n- and p-type GaN

2000 ◽  
Vol 639 ◽  
Author(s):  
D.G. Kent ◽  
K.P. Lee ◽  
A.P. Zhang ◽  
B. Luo ◽  
M.E. Overberg ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Schottky Diodes ◽  
Surface Region ◽  
Chemical Effect ◽  
Near Surface ◽  
Current Voltage ◽  
Extent Of Damage ◽  
P Type ◽  
Dry Etch ◽  
N2 Plasma

ABSTRACTThe extent of damage recovery by N2 plasma treatment of previously damaged n- and p-GaN has been examined using current-voltage (I-V) characteristics from Schottky diodes. There are two contributions to the observed improvement in the I-V characteristics, namely a simple annealing effect and also a chemical effect from reactive nitrogen. However the N2 plasma treatment does not fully restore the initial electrical properties of the near-surface region.

Pulsed Ion Beam Annealing of Metal and Silicide Thin Films on Silicon

1982 ◽  
Vol 40 ◽  
pp. 458-459
Author(s):  
L.J. Chen ◽  
L.S. Hung ◽  
J.W. Mayer
Keyword(s):  
Thin Films ◽  
Ion Beam ◽  
Surface Region ◽  
Molten Layer ◽  
Near Surface ◽  
Contact Materials ◽  
Energy Beam ◽  
Nickel Thin Films ◽  
Metal Silicides ◽  
Silicide Growth

Metal silicides have found increasing use in microelectronic industry as contact materials. Energy beam annealing offers controlled energy deposition in the near surface region so that silicide growth is achieved without heating the entire layer. When pulsed laser and electron at high power density were applied to metal-semiconductor systems, cellular structures have been formed with silicon columns surrounded by silicide walls as a result of the formation of the molten layer of metal and silicon followed by segregation due to constitutional supercooling as the melt front moves toward the surface. A wealth of microstructures were observed in pulsed ion beam annealed nickel thin films on silicon. An interface melting mechanism was invoked to explain the results. In this paper, we report further data on the subject.

Characterization of Si, SiGe and SOI Structures Using Photoluminescence

1999 ◽  
Vol 588 ◽  
Author(s):  
V. Higgs
Keyword(s):  
Focused Ion Beam ◽  
Secondary Ion Mass Spectrometry ◽  
Ion Beam ◽  
Surface Region ◽  
Misfit Dislocations ◽  
Near Surface ◽  
Pl Mapping ◽  
Excitation Laser ◽  
Pl Intensity ◽  
P Type

AbstractA new Photoluminescence (PL) method has been developed to detect defects in the near surface region of Si wafers and Si-on-insulator (SOI) structures. Wafer maps (up to 300 min diameter) can be readily acquired and areas of interest can be scanned at high resolution (≈1 μm). The excitation laser beam is modulated to confine the photogenerated carriers; defects are observed due to the localised reduction of the carrier lifetime. Si p-type (10 Ohm.cm) wafers were intentionally contaminated with various levels of Ni and Fe (1×109−5×1010 atoms/cm2) and annealed. The PL intensity was observed to decrease due to the metal related non-radiative defects. Whereas in contrast, for Cu, (1×109−5×1010 atoms/cm2) the PL intensity actually increased initially and reached a maximum value at 5×109 atoms/cm2. It is suggested that during contamination the Cu related defects have complexed with existing defects (that have stronger recombination properties) and increased the PL. Further Cu contamination (1×1010−5×1010 atoms/cm2) produced a reduction in the PL intensity. PL mapping of strained SiGe epilayers showed that misfit dislocations can be detected and PL can be used to evaluate material quality.PL maps of SOI bonded wafers revealed that the non-bonded areas, voids or gas bubbles could be detected. This was confirmed using defect etching and polishing, voids as small as ≈30 μm in diameter could be detected. SOI wafers fabricated using the separation by implanted oxygen (SIMOX) technique were also analysed, variations in the recombination properties of the layer could be observed. Further inspection using transmission electron microscopy (TEM) revealed that the defects were non-uniformities of the buried oxide covering several microns and containing tetrahedral stacking faults. Focused ion beam (FIB) milling and secondary ion mass spectrometry (SIMS) showed that these defects were at the Si/SiO2 interface and were chemically different to the surrounding area.

Electrical Properties of Epitaxial Silicide-Silicon Interfaces

1985 ◽  
Vol 54 ◽  
Author(s):  
R. T. Tung ◽  
A. F. J. Levi ◽  
J. M. Gibson ◽  
K. K. Ng ◽  
A. Chantre
Keyword(s):  
Fermi Level ◽  
Single Crystal ◽  
Schottky Barrier ◽  
Surface Region ◽  
Ideal Behavior ◽  
Near Surface ◽  
Barrier Heights ◽  
Transmission Electron ◽  
Current Voltage ◽  
P Type

ABSTRACTThe Schottky barrier heights of single crystal NiSi2 layers on Si(111) have been studied by current-voltage, capacitance-voltage and activation energy techniques. Near ideal behavior is found for Schottky barriers grown on substrates cleaned at ∼820°C in ultrahigh vacuum. The Fermi level positions at the interfaces of single crystal type A and type B NiSi2 are shown to differ by ∼0.14 eV. Transmission electron microscopy demonstrated the epitaxial perfection of these suicide layers. At a cleaning temperature of 1050° C, the near surface region of lightly doped n-type Si was converted to p-type. The presence of a p-n junction was directly revealed by spreading resistance measurements and resulted in a high apparent Schottky barrier height (≥0.75 eV) which no longer bears immediate relationship to the interface Fermi level position.

scholarly journals Effect of Photo-Assisted RIE Damage on GaN

2003 ◽  
Vol 8 ◽  
Author(s):  
Z. Mouffak ◽  
N. Medelci-Djezzar ◽  
C. Boney ◽  
A. Bensaoula ◽  
L. Trombetta
Keyword(s):  
Surface Chemistry ◽  
Breakdown Voltage ◽  
Schottky Diode ◽  
Preliminary Data ◽  
Surface Region ◽  
Gas Mixture ◽  
Ion Etching ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
P Type

Reactive Ion Etching (RIE) and Photo-Assisted RIE (PA-RIE) induced damage in GaN using simple Schottky structures and a BCl3/Cl2/N2gas mixture have been investigated. Schottky diode I-V characteristics following different RF powers and exposure times show significant changes caused by damage. This damage results in a reduction of the reverse breakdown voltage VB in n-type GaN and an increase in VB for p-type GaN. Our preliminary data on the PA-RIE process points to much reduced damage levels compared to conventional RIE. This result may be due to a change in surface chemistry or to a photo-enhanced diffusion of defects into the GaN layer, leaving a cleaner near-surface region.

Doping Effects on the Etching Chemistry of GaAs and Si

1990 ◽  
Vol 204 ◽  
Author(s):  
F. A. Houle
Keyword(s):  
Etch Rate ◽  
Driving Forces ◽  
Surface Region ◽  
Near Surface ◽  
Doping Effects ◽  
Independent Mechanism ◽  
Semiconductor Etching ◽  
Surface Intermediates ◽  
Microscopic Picture ◽  
P Type

ABSTRACTDoping effects on semiconductor etching rates have been proposed to be associated with field effects in the near-surface region. Detailed investigations of the chemistry of nand p-type Si and GaAs indicate that the majority carrier can also play an important role in determining the reactivity of surface intermediates, providing an independent mechanism for influencing the etch rate. A microscopic picture of central driving forces in semiconductor etching deduced from the doping cffects is proposed.

Spectroscopic Ellipsometry Study of HgCdTe Epilayer Surfaces During Electron Cyclotron Resonance Plasma Etching

1996 ◽  
Vol 450 ◽  
Author(s):  
J. N. Johnson ◽  
J. H. Dinan ◽  
K. M. Singley ◽  
M. Martinka ◽  
B. Johs
Keyword(s):  
Plasma Etching ◽  
Photoelectron Spectroscopy ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Surface Region ◽  
Auger Spectroscopy ◽  
Electron Cyclotron ◽  
Ex Situ ◽  
Process Conditions ◽  
Near Surface

ABSTRACTSpectroscopie ellipsometry has been used to monitor optical characteristics of HgCdTe surfaces during plasma etching in an electron cyclotron resonance reactor. Commonly used process conditions were found to induce changes in the ellipsometric parameters Δ and φ. A model was constructed to account for these changes in terms of process-induced roughness and mercury depleted sub-surface layers An independent characterization of the near-surface region was earned out ex situ after etching using Auger spectroscopy and x-ray photoelectron spectroscopy. Plasma process parameters were varied to isolate their influence on surface conditions and a set of parameters is given for which changes are minimized.

Monitoring of Dopant Activation in Sub-Surface P-Type Si Using the Surface Charge Profiling (SCP) Method

1996 ◽  
Vol 448 ◽  
Author(s):  
P. Roman ◽  
J. Staffa ◽  
S. Fakhouri ◽  
J. Ruzyllo ◽  
E. Kamieniecki
Keyword(s):  
Surface Charge ◽  
Boron Concentration ◽  
Surface Region ◽  
Ambient Air ◽  
Epitaxial Layers ◽  
Near Surface ◽  
Si Substrates ◽  
Boron Doped ◽  
Order Of Magnitude ◽  
P Type

AbstractIn this study the SCP (Surface Charge Profiling) method, based on non-contact, small-signal ac-SPV measurement is used to study thermal activation of boron in the near surface region of p-type Si wafers. Boron tends to form pairs with impurities such as hydrogen, iron and copper in the near surface region of Si substrates which render it inactive. During device processing, activation of boron may take place resulting in uncontrolled variations in active boron concentration in the near surface region.In this work, both boron doped, polished CZ wafers and wafers with boron doped epitaxial layers are studied. In the former case, the concentration of active boron in the near surface region was initially up to an order of magnitude less than the bulk concentration determined from four-probe measurements, but increased with the temperature of an anneal in ambient air and approached the bulk value. In contrast, the wafers with epitaxial layers showed no consistent variations of surface dopant concentration with temperature. These results confirmed previous findings that the near surface region of the polished wafers is contaminated with metals introduced during polishing operations. The SCP method was found to be very effective in monitoring variations in active boron concentration in the near-surface region.

Sign in / Sign up

Export Citation Format

Share Document