Disordering and Characterization Studies of 69GaAs/71GaAs Isotope Superlattice Structures: The Effect of Outdiffusion of the Substrate Dopant Si

1992 ◽  
Vol 262 ◽  
Author(s):  
T. Y. Tan ◽  
H. M. You ◽  
S. Yu ◽  
U. M. Gitesele ◽  
W. Jäger ◽  
...  
Keyword(s):  
Thermal Equilibrium ◽  
Activation Enthalpy ◽  
N Value ◽  
Temperature Range ◽  
Self Diffusion ◽  
Gaas Substrates ◽  
Characterization Studies ◽  
Superlattice Structures ◽  
Cv Measurements ◽  
P Type

ABSTRACTUndoped 69GaAs/71GaAs isotope superlattice structures grown by MBE on n-type GaAs substrates, doped by Si to ∼3×1018 cm−3, have been used to study Ga self-diffusion in GaAs by disordering reactions. In the temperature range of 850–960°C, the SIMS measured Ga self-diffusivity values showed an activation enthalpy of 4 eV, and are larger than previously compiled Ga self-diffusivity and Al-Ga interdiffusivity values obtained under thermal equilibrium and intrinsic conditions, which are characterized by a 6 eV activation enthalpy. SIMS, CV, and TEM characterizations showed that the as-grown superlattice layers were intrinsic which became p-type with hole concentrations up to ∼2×1017 cm−3 after annealing, because the layers contain carbon. Dislocations of a density of ∼106-107 cm−2 were also present. However, the factor responsible for the presently observed larger Ga self-diffusivity values appears to be Si outdiffusion from the substrate, which was determined using CV measurements. Outdiffusion of Si decreases the n value in the substrate which causes the release of excess Ga vacancies into the superlattice layers where the supersaturated Ga vacancies enhance Ga self-diffusion.

Determination of Diffusivities of Si Self-Diffusion and Si Self-Interstitials using Isotopically Enriched Single-or Multi-30Si Epitaxial Layers

2005 ◽  
Vol 864 ◽  
Author(s):  
S. Matsumoto ◽  
S.R. Aid ◽  
T. Sakaguchi ◽  
K. Toyonaga ◽  
Y. Nakabayashi ◽  
...  
Keyword(s):  
Thermal Equilibrium ◽  
Equilibrium Concentration ◽  
Sample Surface ◽  
Temperature Range ◽  
Self Diffusion ◽  
Si Substrates ◽  
Numerical Fitting ◽  
Si Isotopes ◽  
Secondary Ion

AbstractSelf-diffusivity of Si has been obtained over a wide temperature range (867°C-1300°C) using highly isotopically enriched 30Si epi-layers (99.88%) as a diffusion source into natural Si substrates. 30Si epi-layers were grown on both CZ-Si substrates and non-doped epi-layers grown on CZ-Si substrates using low pressure CVD with 30SiH4. Diffusion was performed in resistance-heated furnaces under a pure Ar atmosphere. After annealing, the concentrations of the respective Si isotopes were measured with secondary ion mass spectroscopy (SIMS). Diffusivity of 30Si (called Si self-diffusivity, DSD) was determined using a numerical fitting process with 30Si SIMS profiles. We found no major differences in self-diffusivity between bulk Si and epi-Si. Within the 867°C -1300°C range investigated, DSD can be described by an Arrhenius equation with one single activation enthalpy: DSD =14 exp (—4.37 eV/kT) cm2/s. The present result is in good agreement with that of Bracht et. al.Diffusivity and thermal equilibrium concentration of Si self-interstitials have been determined using multi-30Si epi-layers consisting of alternative layers with isotopically pure 30Si and natural Si. The sample surface was oxidized and the Si self-interstitials were introduced from the surface. Spreading of 30Si spikes of each layer due to the diffusion of Si self-interstitials generated at the surface was measured with SIMS analysis. The diffusivity of Si self-interstitials, DI, is obtained by fitting with experimental results. In the temperature range between 820 -920°C, DI and thermal equilibrium concentration of Si self-interstitials, CIi, are described by the Arrhenius equations DI3.48×104 exp (—3.82eV/KT) cm2/s and CIi= 9.62×1018 exp (—0.475eV/KT) cm-3, respectively.

Determination of Ga Self-Diffusion Coefficient in GaAs

1991 ◽  
Vol 240 ◽  
Author(s):  
T. Y. Tan ◽  
S. Yu ◽  
U. Gösele
Keyword(s):  
Diffusion Coefficient ◽  
Quantitative Determination ◽  
Thermal Equilibrium ◽  
Activation Enthalpy ◽  
Self Diffusion ◽  
Self Diffusion Coefficient ◽  
Positively Charged

ABSTRACTA quantitative determination of the contributions of the triply-negatively charged Ga vacancies and of the doubly-positively charged Ga self-interstitials to Ga self-diffusion coefficient in GaAs has been carried out. Unde thermal equilibrium and intrinsic conditions, the contribution is characterized by an activation enthalpy of 6 eV for As-rich crystals and of 7.52 eV for Ga-rich crystals, while the contribution is characterized by an activation enthalpy of 4.89 eV for As-rich crystals and of 3.37 eV for Ga-rich crystals.

Nitrogen Self-Diffusion in Polycrystalline Si3N4 Films: Isotope Heterostructures vs. Gas-Exchange

2005 ◽  
Vol 237-240 ◽  
pp. 512-517 ◽  
Author(s):  
Harald Schmidt ◽  
Günter Borchardt ◽  
Mario Rudolphi ◽  
H. Baumann ◽  
Michael Bruns ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Exchange ◽  
Activation Enthalpy ◽  
Diffusion Mechanism ◽  
Exchange Process ◽  
Exchange Method ◽  
Surface Exchange ◽  
Exponential Factor ◽  
Temperature Range ◽  
Self Diffusion

The self-diffusion of nitrogen is investigated in polycrystalline thin silicon nitride films using a gas-exchange method (14N2/Si3 15N4) in comparison to Si3 14N4/Si3 15N4/Si3 14N4 isotope heterostructures. The films are produced by reactive r. f. magnetron sputtering. Depth profile analysis is carried out with secondary ion mass spectrometry (SIMS), secondary neutral mass spectrometry (SNMS), and nuclear resonant reaction analysis (NRRA). The nitrogen diffusivities determined with the use of isotope heterostructures follow an Arrhenius law in the temperature range between 1200 and 1700 °C with an activation enthalpy of DH = 4.9 eV and a pre-exponential factor of D0 = 1 x 10-6 m2/s, indicating a conventional diffusion mechanism via localized point defects. Using the gas-exchange method, the nitrogen diffusivities could be obtained only in the temperature range between 1600 and 1700 °C. This is due to the fact that at temperatures below 1600 °C the surface exchange process with its high activation enthalpy (about 10 eV) is rate limiting, leading to non detectable diffusion profiles. The application of the different methods of depth profiling leads to the same diffusivities within estimated errors.

OXYCHALCOGENIDES AS NEW EFFICIENT p-TYPE THERMOELECTRIC MATERIALS

2013 ◽  
Vol 06 (05) ◽  
pp. 1340007 ◽  
Author(s):  
CELINE BARRETEAU ◽  
LIN PAN ◽  
YAN-LING PEI ◽  
LI-DONG ZHAO ◽  
DAVID BERARDAN ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Parent Compound ◽  
Thermoelectric Figure ◽  
Medium Temperature ◽  
Temperature Range ◽  
The Past ◽  
Thermoelectric Conversion ◽  
New Directions ◽  
Wide Scale ◽  
P Type

During the past two years, we have underlined the great potential of p-type oxychalcogenides, with parent compound BiCuSeO , for thermoelectric applications in the medium temperature range (400–650°C). These materials, which do not contain lead and are less expensive than Te containing materials, exhibit large thermoelectric figure of merit, exceeding 1 in a wide temperature range, mainly due to an intrinsically very low thermal conductivity. This paper summarizes the main chemical and crystallographic features of this system, as well as the thermoelectric properties. It also gives new directions to improve these properties, and discuss the potential of these materials for wide scale applications in thermoelectric conversion system in the medium temperature range.

LIGHT-INDUCED EXCESS CONDUCTIVITY AND THE ROLE OF ARGON IN THE DEPOSITION OF DOPING-MODULATED AMORPHOUS SILICON SUPERLATTICES.

1985 ◽  
Vol 56 ◽  
Author(s):  
F.-C. Su ◽  
S. Levine ◽  
P. E. Vanier ◽  
F. J. Kampas
Keyword(s):  
Amorphous Silicon ◽  
Amorphous Semiconductor ◽  
Excess Conductivity ◽  
The Novel ◽  
Semiconductor Superlattice ◽  
Deposition Parameters ◽  
Superlattice Structures ◽  
Argon Dilution ◽  
P Type

AbstractAmorphous semiconductor superlattice structures consisting of alternating n-type and p-type doped layers of hydrogenated amorphous silicon (a-Si:H) have been made by silane glow discharge in a single chamber system. These multilayered films show the novel phenomenon of light-induced excess conductivity (LEC) associated with a metastable state having a lifetime of order of days. This report shows that the LEC effect is quite dependent on the specific details of the deposition parameters, namely dilution of the silane with inert gas, substrate temperature and layer thickness. In order to investigate the origin of the LEC effect, argon dilution was used for specific regions of the structure. This experiment shows that the slow states are distributed throughout the layers, and are not concentrated at the interfaces.

scholarly journals Self- and Dopant Diffusion in Extrinsic Boron Doped Isotopically Controlled Silicon Multilayer Structures

2002 ◽  
Vol 719 ◽  
Author(s):  
Ian D. Sharp ◽  
Hartmut A. Bracht ◽  
Hughes H. Silvestri ◽  
Samuel P. Nicols ◽  
Jeffrey W. Beeman ◽  
...  
Keyword(s):  
Multilayer Structure ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Processes ◽  
Quantitative Description ◽  
Multilayer Structures ◽  
Dopant Diffusion ◽  
Enhanced Diffusion ◽  
Self Diffusion ◽  
Boron Doped ◽  
P Type

AbstractIsotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. 30Si was used as a tracer through a multilayer structure of alternating natural Si and enriched 28Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850°C and 1100°C. A specially designed ion-implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

Si1−xGex Bulk Crystals Growth and PN Junction Formation by Diffusing Phosphorus

1999 ◽  
Vol 607 ◽  
Author(s):  
S. Kato ◽  
T. Horikoshi ◽  
T. Ohkubo ◽  
T. Iida ◽  
Y. Takano
Keyword(s):  
Silicon Germanium ◽  
Bulk Crystals ◽  
Temperature Dependent ◽  
Alloy Scattering ◽  
Self Diffusion ◽  
Pn Junction ◽  
Current Voltage ◽  
Vertical Bridgman ◽  
Current Voltage Characteristics ◽  
P Type

AbstractThe bulk crystal of silicon germanium was grown by vertical Bridgman method with germanium composition, x, varying from 0.6 to 1.0. The temperature dependent variation of the mobility is indicative of alloy scattering dominantly for the bulk wafer. Phosphorus was diffused in as-grown p-type bulk wafer at 850 °C to form pn-junction, and the diffusion coefficient of phosphorus was evaluated as a function of x. The diffusion behavior of phosphorus in silicon germanium is closely correlated with the germanium self-diffusion with changing x. For specimens with lower content x, P concentration profiles indicated “kink and tail” shape, while it was not observed for higher x. For current-voltage characteristics measurement, an ideality factor was obtained.

Thermal Conductivity of Si/SiGe Superlattices

2001 ◽  
Author(s):  
Scott T. Huxtable ◽  
Alexis R. Abramson ◽  
Arun Majumdar ◽  
Chang-Lin Tien ◽  
Chris LaBounty ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Measurement Technique ◽  
Unit Length ◽  
Temperature Range ◽  
Sige Alloy ◽  
The Cross ◽  
Superlattice Structures

Abstract The cross-plane and in-plane thermal conductivity of four Si/Si0.7Ge0.3 superlattice structures with periods from 45 Å to 300 Å are experimentally investigated using the 3-ω measurement technique. The experiment is conducted over a temperature range from 70 to 340 K. Results indicate that the cross-plane thermal conductivity decreases with decreasing period thickness (i.e. increasing number of interfaces per unit length). The superlattice with the shortest period exhibits a cross-plane thermal conductivity similar to that of a SiGe alloy. The in-plane thermal conductivity follows a similar decreasing trend with period thickness for the three larger period superlattices, but jumps to higher values for the shortest period superlattice. Additionally, the in-plane conductivity can be 3–4 times higher than the cross-plane value.

High Gain and High Sensitive Blue-Ultraviolet Avalanche Photodiodes (APDs) of ZnSSe n+-i-p Structure Molecular Beam Epitaxy (MBE) Grown on p-type GaAs Substrates

2005 ◽  
Vol 44 (No. 17) ◽  
pp. L508-L510 ◽  
Author(s):  
Tomoki Abe ◽  
Koshi Ando ◽  
Katsushi Ikumi ◽  
Hiroyasu Maeta ◽  
Junji Naruse ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Avalanche Photodiodes ◽  
High Gain ◽  
Gaas Substrates ◽  
P Type
Sign in / Sign up

Export Citation Format

Share Document