The Properties Of a-Si:H/c-Si Heterostructures Prepared By 55 kHz Pecvd For Solar Cell Application

1997 ◽  
Vol 485 ◽  
Author(s):  
B. G Budaguan ◽  
A. A. Aivazov ◽  
A. A. Sherchenkov ◽  
A. V Blrjukov ◽  
V. D. Chernomordic ◽  
...  
Keyword(s):  
Crystalline Silicon ◽  
Low Frequency ◽  
Reverse Current ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Solar Cell Application ◽  
Current Voltage ◽  
Frequency Plasma ◽  
Device Applications

AbstractIn this work a-Si:H/c-Si heterostructures with good electronic properties of a-Si:H were prepared by 55 kHz Plasma Enhanced Chemical Vapor Deposition (PECVD). Currentvoltage and capacitance-voltage characteristics of a-Si:H/c-Si heterostructures were measuredto investigate the influence of low frequency plasma on the growing film and amorphous silicon/crystalline silicon boundary. It was established that the interface state density is low enough for device applications (<2.1010 cm−2). The current voltage measurements suggest that, when forward biased, space-charge-limited current determines the transport mechanism in a- Si:H/c-Si heterostructures, while reverse current is ascribed to the generation current in a-Si:H and c-Si depletion layers.

Heterojuncion Study of Ga0.92In08as(P+)/GaAs(n) Diodes: Correlation of Electrical and Strucrural Characteristics

1989 ◽  
Vol 160 ◽  
Author(s):  
Y.W. Choi ◽  
C.R. Wie ◽  
K.R. Evans ◽  
C.E. Stutz
Keyword(s):  
Low Frequency ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Trap Level ◽  
Fermi Level Pinning ◽  
Pinning Effect ◽  
Quasi Fermi Level ◽  
Current Voltage ◽  
Capacitance Voltage

AbstractDifferent in-plane mismatch was introduced by varying the Ga 0.92In0.08As(p+) epilayer thickness (h-0.1, 0.25, 0.5 and lum) on GaAs(n)/GaAs(n+) structure. For sample with h-lum, quasi-Fermi level pinning effect was observed in low temperature forward Current-Voltage characteristic due to high density misfit dislocation. From Vint measurement at low frequency limit in C-2 vs Voltage plot, interface state density Nss was obtained. From Capacitance-Voltage measurements at different frequencies, single-level interface state density Ns was estimated using Schokley-Read-Hall statistics. Both Nss and Ns show their linear relation with epilayer in-plane mismatch. Admittance Spectroscopy shows an interface trap level at about Ev + 0.36 eV with the hole capture cross section cp = 2.7×10-15 cm-2 for the h-lum sample, and at Ev + 0.21 eV with cP = 2.4×10-16 cm-2 for the h-0.5um sample.

Sub-gap Photoconductivity in Germanium-silicon Films Deposited by Low Frequency Plasma

2010 ◽  
Vol 1245 ◽  
Author(s):  
Andrey Kosarev ◽  
Francisco Avila
Keyword(s):  
Photon Energy ◽  
Low Frequency ◽  
Chemical Vapor ◽  
Defect States ◽  
Constant Intensity ◽  
Characteristic Energy ◽  
Frequency Plasma ◽  
Device Applications ◽  
Si Films ◽  
Germanium Silicon

Abstract(GexSi1-x:H) films are of much interest for many device applications because of narrow band gap and compatibility with films deposited by plasma. However, electronic properties of GexSi1-x:H films for high Ge content x > 0.5 have been studied less than those of Si films. In this work, we present a study of sub-gap photoconductivity (σpc) in GexSi1-x:H films for x = 1 and x = 0.97 deposited by low frequency plasma enhanced chemical vapor deposition (LF PECVD) with both various H-dilution (RH) during growth (non-doped films) and boron (B) incorporation in the films. Spectra of sub-gap photoconductivity σpc(hν) were measured in the photon energy range of hν = 0.6 to 1.8 eV. σpc(hν) spectra were normalized to constant intensity. For hν < Eg two regions in σpc(hν) can be distinguished: “A”, where σpc is related to transitions between tail and extended states, and “B”, where photoconductivity is due to defect states. σpc(hν) in ”A” region showed exponential behavior that could be described by some characteristic energy EUPC similar to Urbach energy EU in spectral dependence of optical absorption. EUPC > EU was observed in all the films studied. This together with higher relative values (i.e. normalized by the maximum value at hν = Eg) for photoconductivity comparing with those for α means that mobility-lifetime product (μτ) depends on photon energy μτ = f(hν) that was determined from α(hν)and σpc(hν). μτ(hν) increases by factor of 20 to 40 depending on the sample with reducing hν from 1.1 to 0.7 eV. In some samples, this dependence was monotonous, while in others demonstrated maxima related to both interference and density of states. Effects of both RH and boron incorporation have been found and are discussed.

Identification of Charging Effects in Plasma-Enhanced TEOS Deposition with Non-Contact Test Techniques

1998 ◽  
Author(s):  
Tomasz Brozek ◽  
James Heddleson
Keyword(s):  
Vapor Deposition ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Wafer Surface ◽  
Oxide Charge ◽  
Contact Test ◽  
Deposition Power ◽  
Oxide Deposition

Abstract Use of non-contact test techniques to characterize degradation of the Si-SiO2 system on the wafer surface exposed to a plasma environment have proven themselves to be sensitive and useful in investigation of plasma charging level and uniformity. The current paper describes application of the surface charge analyzer and surface photo-voltage tool to explore process-induced charging occurring during plasma enhanced chemical vapor deposition (PECVD) of TEOS oxide. The oxide charge, the interface state density, and dopant deactivation are studied on blanket oxidized wafers with respect to the effect of oxide deposition, power lift step, and subsequent annealing.

Properties of Thin SiO2 Films with In-Situ Deposition of Poly Si Electrodes

1989 ◽  
Vol 146 ◽  
Author(s):  
Paihung Pan ◽  
Ahmad Kermani ◽  
Wayne Berry ◽  
Jimmy Liao
Keyword(s):  
Electrical Properties ◽  
Breakdown Strength ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
In Situ Deposition ◽  
Different Temperatures ◽  
Flatband Voltage ◽  
Si Films

ABSTRACTElectrical properties of thin (12 nm) SiO2 films with and without in-situ deposited poly Si electrodes have been studied. Thin SiO2 films were grown by the rapid thermal oxidation (RTO) process and the poly Si films were deposited by the rapid thermal chemical vapor deposition (RTCVD) technique at 675°C and 800°C. Good electrical properties were observed for SiO2 films with thin in-situ poly Si deposition; the flatband voltage was ∼ -0.86 V, the interface state density was < 2 × 1010/cm2/eV, and breakdown strength was > 10 MV/cm. The properties of RTCVD poly Si were also studied. The grain size was 10-60 rim before anneal and was 50-120 rim after anneal. Voids were found in thin (< 70 nm) RTCVD poly Si films. No difference in either SiO2 properties or poly Si properties was observed for poly Si films deposited at different temperatures.

scholarly journals A Study of a-Sic/C-Si(n) Isotype Heterojunctions

1993 ◽  
Vol 16 (1) ◽  
pp. 55-64 ◽  
Author(s):  
N. Georgoulas ◽  
L. Magafas ◽  
A. Thanailakis
Keyword(s):  
Temperature Dependence ◽  
Crystalline Silicon ◽  
Diffusion Mechanism ◽  
Thermionic Emission ◽  
Reverse Current ◽  
Emission Mechanism ◽  
Drift Diffusion ◽  
Si Substrates ◽  
Current Voltage ◽  
Capacitance Voltage

In the present work a study of the electrical properties of heterojunctions between rf sputtered amorphous silicon carbide (a-SiC) thin films and n-type crystalline silicon (c-Si) substrates is reported. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics, as well as the temperature dependence of the current of a-SiC/c-Si(n) heterojunctions were measured. The I-V characteristics of a-SiC/ c-Si(n) heterojunctions exhibit poor rectification properties, with a high reverse current, at higher temperatures (T > 250K), whereas good rectification properties are obtained at lower temperatures (T < 250K). It was found that the a-SiC/c-Si(n) heterojunctions are isotype, suggesting that-the conductivity of a-SiC is n-type. The temperature dependence of the current (from 185K to 320K) showed that the majority carriers of c-Si(n) (i.e. electrons) are transported from c-Si(n) to a-SiC mainly by the thermionic emission mechanism, or by the drift-diffusion mechanism. From C-V measurements of a-SiC/c-Si(n) heterojunctions the electron affinity of a-SiC was found to be X1= 4.20 ± 0.04 eV. Finally, the a-SiC/ c-Si(n) isotype heterojunctions are expected to be interesting devices as infrared

Investigation of the off-current in amorphous silicon thin film transistors for SiO2 and SiNx. gate insulators

1996 ◽  
Vol 424 ◽  
Author(s):  
Jeong Hyun Kim ◽  
Woong Sik Choi ◽  
Chan Hee Hong ◽  
Hoe Sup Soh
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Defect States ◽  
Silicon Thin Film ◽  
Pressure Chemical

AbstractThe off current behavior of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) with an atmospheric pressure chemical vapor deposition (APCVD) silicon dioxide (SiO2) gate insulator were investigated at negative gate voltages. The a-Si:H TFT with SiO2 gate insulator has small off currents and large activation energy (Ea) of the off current compared to the a-Si:H TFT with SiNx gate insulator. The holes induced in the channel by negative gate voltage seem to be trapped in the defect states near the a-Si:H/SiO2 interface. The interface state density in the lower half of the band gap of a-Si:H/SiO2 appears to be much higher than that for a-Si:H/SiNx.

Low- and High-Frequency C–V Characteristics of Au/n-GaN/n-GaAs

2018 ◽  
Vol 18 (06) ◽  
pp. 1850039
Author(s):  
Abderrezzaq Ziane ◽  
Mohamed Amrani ◽  
Abdelaziz Rabehi ◽  
Zineb Benamara
Keyword(s):  
Schottky Diode ◽  
High Frequency ◽  
High Vacuum ◽  
Low Frequency ◽  
Interface State ◽  
Interface States ◽  
State Density ◽  
Ultra High Vacuum ◽  
Active Nitrogen ◽  
Capacitance Voltage

Au/GaN/GaAs Schottky diode created by the nitridation of n-GaAs substrate which was exposed to a flow of active nitrogen created by a discharge source with high voltage in ultra-high vacuum with two different thicknesses of GaN layers (0.7[Formula: see text]nm and 2.2[Formula: see text]nm), the I–V and capacitance–voltage (C–V) characteristics of the Au/n-GaN/n-GaAs structures were studied for low- and high-frequency at room temperature. The measurements of I–V of the Au/n-GaN/n-GaAs Schottky diode were found to be strongly dependent on bias voltage and nitridation process. The electrical parameters are bound by the thickness of the GaN layer. The capacitance curves depict a behavior indicating the presence of interface state density, especially in the low frequency. The interface states density was calculated using the high- and low-frequency capacitance curves and it has been shown that the interface states density decreases with increasing of nitridation of the GaAs.

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