Ion Implantation Doping of Semi-Insulating Polycrystalline Silicon

1993 ◽  
Vol 316 ◽  
Author(s):  
Salvatore Lombardo ◽  
S. U. Campisano
Keyword(s):  
Grain Boundary ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Thermionic Emission ◽  
Threshold Value ◽  
Threshold Level ◽  
Room Temperature Resistivity ◽  
Undoped Material ◽  
Donor And Acceptor ◽  
And Diffusion

ABSTRACTThe study of doping of silicon nano-grains in semi-insulating polycrystalline silicon is of paramount importance since intense room-temperature luminescence at 1.54 µm has been demonstrated in this silicon-based semiconductor when doped with erbium ions. We have investigated the formation of p- and n-type layers of semi-insulating polycrystalline silicon by implantation and diffusion of B, P, As, and Er. The room-temperature resistivity can be changed by more than six orders of magnitude for both p- and n-type doping. A dramatic decrease of resistivity is observed for dopant concentrations above a threshold level; this effect is explained by assuming that the free-carrier motion is limited by grain boundary barriers and the electrical conduction is due to thermionic emission and tunneling of the carriers through the barriers. The prevalence of one mechanism over the other depends upon temperature, oxygen concentration and doping. In the undoped material the barrier height is large (≈ 0.5 eV), but for dopant concentrations above the threshold, it decreases with the doping level. Correspondingly, the conductivity increases by many orders of magnitude. The determination of the threshold value allows the evaluation of donor and acceptor grain boundary trap densities. Diodes have been fabricated by implantation and diffusion of boron and erbium. The I-V characteristics of these diodes are interpreted on the basis of the material modeling.

scholarly journals Carrier Transport in Ultra-Thin Nano/Polycrystalline Silicon Films and Nanowires

2001 ◽  
Vol 664 ◽  
Author(s):  
Toshio Kamiya ◽  
Yong T. Tan ◽  
Yoshikazu Furuta ◽  
Hiroshi Mizuta ◽  
Zahid A.K. Durrania ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Polycrystalline Silicon ◽  
Carrier Transport ◽  
Crystalline Silicon ◽  
Thermionic Emission ◽  
Nanocrystalline Silicon ◽  
Silicon Films ◽  
Si Nanowires ◽  
Potential Barriers ◽  
Boundary Potential

ABSTRACTCarrier transport was investigated in two different types of ultra-thin silicon films, polycrystalline silicon (poly-Si) films with large grains > 20 nm in size and hydrogenated nanocrystalline silicon (nc-Si:H) films with grains 4 nm – 8 nm in size. It was found that there were local non-uniformities in grain boundary potential barriers in both types of films. Single-electron charging effects were observed in 30 nm × 30 nm nanowires fabricated in 30 nm-thick nc-Si:H films, where the electrons were confined in crystalline silicon grains encapsulated by amorphous silicon. In contrast, the poly-Si nanowires of similar dimensions showed thermionic emission over the grain boundary potential barriers formed by carrier trapping in grain boundary defects.

Conduction in Polycrystalline Silicon: Generalized Thermionic Emission-Diffusion Theory and Extended State Mobility Model

1982 ◽  
Vol 13 ◽  
Author(s):  
A.N. Khondker ◽  
D.M. Kim ◽  
R.R. Shah
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Grain Boundary ◽  
Material Properties ◽  
Polycrystalline Silicon ◽  
Diffusion Theory ◽  
Thermionic Emission ◽  
Mobility Model ◽  
Extended State ◽  
Thermionic Field Emission

ABSTRACTWe present a general theory of conduction in polysilicon. The theoretical framework reconciles two apparently divergent approaches for modeling conduction processes in polysilicon and provides a physical basis to correctly interpret and to point out the deficiencies of previously reported thermionic and thermionic field emission theory. This model is based on an extended state mobility in the disordered grain boundary and the thermionic emission-diffusion theory for conduction of current. The attractive features of our theory are (a) it can explain the experimental data without the use of an artificial factor, f, (b) the conduction process is characterized explicitly by the inherent material properties of the grain and the grain boundary. Our model is particularly suited for describing the electrical properties of laser restructured polysilicon, where because of large grain size the diffusion process is expected to be dominant.

Growth of Undoped (Vanadium-Free) Semi-Insulating 6H-SiC Single Crystals

2005 ◽  
Vol 483-485 ◽  
pp. 35-38 ◽  
Author(s):  
Thomas Anderson ◽  
Donovan L. Barrett ◽  
J. Chen ◽  
Ejiro Emorhokpor ◽  
A. Gupta ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Single Crystals ◽  
High Purity ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Undoped Material ◽  
Barrier Capacitance ◽  
P Type ◽  
Temperature Resistivity ◽  
Equal Density

II-VI has developed an Advanced PVT (APVT) process for the growth of nominally undoped (vanadium-free) semi-insulating 2” and 3” diameter 6H-SiC crystals with room temperature resistivity up to 1010 W·cm. The process utilizes high-purity SiC source and employs special measures aimed at the reduction of the impurity background. The APVT-grown material demonstrates concentrations of B and N reduced to about 2·1015cm-3. Wafer resistivity has been studied and correlated with Schottky barrier capacitance, yielding the density of deep compensating centers in 6H-SiC in the low 1015 cm-3 range for both ntype and p-type material. The nearly equal density of deep donors and deep acceptors ndicates that the centers responsible for the intrinsic compensation can be amphoteric. TheEPR density of spins from free carbon vacancies is about 1014 cm-3. It is also hypothesized that impurity-vacancy complexes can be present in the undoped material and participate in compensation.

'The Role of the Grain Boundary on the Resistivity of Pb(Fe1/2Nb1/2)O3 at Room Temperature

2002 ◽  
Vol 718 ◽  
Author(s):  
Sang-Bop Lee ◽  
Kwang-Ho Lee ◽  
Hwan Kim
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Sintered Specimen ◽  
Room Temperature Resistivity ◽  
Boundary Properties ◽  
Order Of Magnitude ◽  
The Difference ◽  
Fe Reduction ◽  
Temperature Resistivity

AbstractThe effect of changing sintering temperature on the grain boundary properties and the room temperature resistivity (ρRT) of Pb(Fe1/2Nb1/2)O3 (PFN) was investigated. Monitering the temperature dependence of resistivity showed that the ρRT's of 1050°C and 1150°C-sintered specimen were 1011ΩEcm and 104ΩEcm respectively, but the resistivity above 300°C became nearly identical. The previous model, that the low resistivity of PFN is due to the electron hopping between Fe2+ and Fe3+ driven by the reduction of PFN, couldn't explain this phenomenon, and the reconsideration of the Fe reduction revealed that the difference of electron concentration between the 1050°C and 1150°C-sintered specimen couldn't exceed one order of magnitude. The role of the grain boundary was introduced in order to account for this phenomenon.

Depth Variation of Transport Parameters in Poly-Si Under Am1 Illumination

1990 ◽  
Vol 182 ◽  
Author(s):  
Z. Chen ◽  
L.C. Burton
Keyword(s):  
Electron Transport ◽  
Grain Boundary ◽  
Electronic Properties ◽  
Computer Modeling ◽  
Barrier Height ◽  
Polycrystalline Silicon ◽  
Diffusion Length ◽  
Electron Lifetime ◽  
Transport Parameters ◽  
And Diffusion

Abstract; Grain boundary (GB) recombination is a controlling factor in the electronic properties of polycrystalline silicon. We would like to report computer modeling of the variation of electron transport parameters with depth, under illumination. The GB barrier height (Vg) versus photogeneration rate G and depth are presented, along with the resulting electron lifetime (π), mobility (µ) and diffusion length (L). Under AM1 illumination, Vg increases whereas -π, µ and L all decrease drastically with increasing depth. The GB trap density is used as a parameter, and strongly influences transport parameters in both dark and light cases.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

EVOLUTIONS OF GRAIN BOUNDARY RECOMBINATION ACTIVITY IN POLYCRYSTALLINE SILICON INVESTIGATED BY LBIC MAPPING AND DLTS

1989 ◽  
Vol 50 (C6) ◽  
pp. C6-160-C6-160
Author(s):  
M. PASQUINELLI ◽  
N. M'GAFFAD ◽  
H. AMANRICH ◽  
S. MARTINUZZI
Keyword(s):  
Grain Boundary ◽  
Polycrystalline Silicon ◽  
Recombination Activity
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