The Heteroepitaxy and Characterization of Inp and GaInP on Silicon for Solar Cell Applications

ABSTRACTInP and GaInP layers were heteroepitaxially grown on (100) Si substrates by atmospheric pressure MOCVD. TEM and photoluminescence (PL) were used to measure the defect density and the minority carrier lifetime in these structures. The direct growth of InP on Si resulted in either polycrystalline or heavily faulted single-crystal layers. The use of GaAs buffer layers in InP/Si structures gave rise to significantly improved morphology and reduced the threading dislocation density. The best InP/Si layers in this study were obtained by using GaAs-GaInAs graded buffers. Additionally, the growth of high quality GaInP on Si was demonstrated. The minority carrier lifetime of 7 ns in these layers is the highest of any III-V/Si semiconductor measured in our laboratory.

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The Reduction of The Defect Density in CdTe Buffer Layers for The Growth of HgCdTe Infrared Photodiodes on Si (211) Substrates

MRS Proceedings ◽

10.1557/proc-484-329 ◽

1997 ◽

Vol 484 ◽

Cited By ~ 1

Author(s):

H.-Y. Wei ◽

L. Salamanca-Riba ◽

N. K. Dhar

Keyword(s):

Dislocation Density ◽

Defect Density ◽

Three Dimensional ◽

Buffer Layers ◽

Threading Dislocation ◽

Si Substrates ◽

Migration Enhanced Epitaxy ◽

Threading Dislocation Density ◽

Order Of Magnitude ◽

Cdte Buffer

CdTe epilayers were grown by molecular beam epitaxy on As-passivated nominal (211) Si substrates using thin interfacial ZnTe layers. By using thin recrystallized (initially amorphous) ZnTe buffei layers, we utilized migration enhanced epitaxy (MEE) in the ZnTe layer and overcome the tendency toward three dimensional nucleation. The threading dislocation densities in 8–9 tm thick CdTe films deposited on the recrystallized amorphous ZnTe films were in the range of 2 to 5 × 105 cm−2. In addition to the reduction of threading dislocation density, the interface between the ZnTe layers and the Si substrate is much smoother and the microtwin density is an order of magnitude lower than in regular MEE growth. In order to understand the initial nucleation mechanism of the ZnTe on the As precursor Si surface, we also grew ZnTe epilayers on Te precursor treated Si substrates. The growth mode, microtwin density, and threading dislocation density are compared for films grown on Si substrates with different surface precursors and grown by different growth methods.

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The Reduction of The Defect Density in CdTe Buffer Layers for The Growth of HgCdTe Infrared Photodiodes on Si (211) Substrates

MRS Proceedings ◽

10.1557/proc-487-607 ◽

1997 ◽

Vol 487 ◽

Cited By ~ 2

Author(s):

H.-Y. Wei ◽

L. Salamanca-Riba ◽

N. K. Dhar

Keyword(s):

Dislocation Density ◽

Defect Density ◽

Three Dimensional ◽

Buffer Layers ◽

Threading Dislocation ◽

Si Substrates ◽

Migration Enhanced Epitaxy ◽

Threading Dislocation Density ◽

Order Of Magnitude ◽

Cdte Buffer

CdTe epilayers were grown by molecular beam epitaxy on As-passivated nominal (211) Si substrates using thin interfacial ZnTe layers. By using thin recrystallized (initially amorphous) ZnTe buffer layers, we utilized migration enhanced epitaxy (MEE) in the ZnTe layer and overcome the tendency toward three dimensional nucleation. The threading dislocation densities in 8–9 μm thick CdTe films deposited on the recrystallized amorphous ZnTe films were in the range of 2 to 5 × 105 cm−2. In addition to the reduction of threading dislocation density, the interface between the ZnTe layers and the Si substrate is much smoother and the microtwin density is an order of magnitude lower than in regular MEE growth. In order to understand the initial nucleation mechanism of the ZnTe on the As precursor Si surface, we also grew ZnTe epilayers on Te precursor treated Si substrates. The growth mode, microtwin density, and threading dislocation density are compared for films grown on Si substrates with different surface precursors and grown by different growth methods.

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Development of High-Performance GaAs Solar Cells on Large-Grain Polycrystalline Ge Substrates

MRS Proceedings ◽

10.1557/proc-403-483 ◽

1995 ◽

Vol 403 ◽

Cited By ~ 1

Author(s):

R. Venkatasubramanian ◽

B. O'Quinn ◽

J. S. Hills ◽

M. L. Timmons ◽

D. P. Malta

Keyword(s):

Solar Cells ◽

High Performance ◽

Carrier Lifetime ◽

Minority Carrier ◽

Minority Carrier Lifetime ◽

Cross Sectional ◽

Plan View ◽

Electron Beam Induced Current ◽

Induced Defects

AbstractThe characterization of MOCVD-grown GaAs-AlGaAs materials and GaAs p+n junctions on poly-Ge substrates is presented. Minority carrier lifetime in GaAs-AIGaAs double-hetero (DH) structures grown on these substrates and the variation of lifetimes across different grainstructures are discussed. Minority-carrier diffusion lengths in polycrystalline GaAs p+-n junctions were evaluated by cross-sectional electron-beam induced current (EBIC) scans. The junctions were also studied by plan-view EBIC imaging. Optimization studies of GaAs solar cell on poly-Ge are discussed briefly. The effect of various polycrystalline substrate-induced defects on performance of GaAs solar cells are presented.

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Mobility-Lifetime Products in a-Si:H and the Dangling Bond Recombination Model

MRS Proceedings ◽

10.1557/proc-258-765 ◽

1992 ◽

Vol 258 ◽

Cited By ~ 2

Author(s):

E. Morgado

Keyword(s):

Fermi Level ◽

Carrier Lifetime ◽

Minority Carrier ◽

Defect Density ◽

Minority Carrier Lifetime ◽

Localized States ◽

Correlated Electrons ◽

Recombination Model ◽

Model Equations ◽

Determinant Factor

ABSTRACTFermi level and light intensity dependences of electron and hole lifetimes have been calculated using a recombination model which considers positively correlated dangling bonds as the only localized states in the gap. The model equations have been solved numerically taking into account the non-equilibrium statistics of correlated electrons and the Fermi level dependence of the defect density. The results are in agreement with the anticorrelated behavior of the majority' and minority carrier μτ products observed in a-Si:H. The majority carrier lifetime is found to be more sensitive to the photogeneration rate than the minority carrier lifetime. The position of the Fermi level with respect to the energies of the D° and D- centers in the gap is a determinant factor of the (°τ)e/(μτ)h ratio.

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Evaluation of Four Imaging Techniques for the Electrical Characterization of Solar Cells

MRS Proceedings ◽

10.1557/proc-1123-1123-p03-08 ◽

2008 ◽

Vol 1123 ◽

Cited By ~ 2

Author(s):

Gregory M. Berman ◽

Nathan J. Call ◽

Richard K. Ahrenkiel ◽

Steven W. Johnston

Keyword(s):

Solar Cells ◽

Carrier Lifetime ◽

Minority Carrier ◽

Diffusion Length ◽

Imaging Techniques ◽

Electrical Characterization ◽

Minority Carrier Lifetime ◽

Industry Standards ◽

Lock In

AbstractWe evaluate four techniques that image minority carrier lifetime, carrier diffusion length, and shunting in solar cells. The techniques include photoluminescence imaging, carrier density imaging, electroluminescence imaging, and dark lock-in thermography shunt detection. We compare these techniques to current industry standards and show how they can yield similar results with higher resolution and in less time.

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Minority Carrier Lifetime Measurement in HF Solution to Evaluate Si Substrates for Solar Cells

Japanese Journal of Applied Physics ◽

10.1143/jjap.29.l166 ◽

1990 ◽

Vol 29 (Part 2, No. 1) ◽

pp. L166-L168 ◽

Cited By ~ 5

Author(s):

Takayuki Nammori ◽

Koji Okamoto ◽

Tohru Nunoi ◽

Yutaka Hayashi

Keyword(s):

Solar Cells ◽

Carrier Lifetime ◽

Minority Carrier ◽

Minority Carrier Lifetime ◽

Lifetime Measurement ◽

Si Substrates

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Optimisation Of The Heteroepitaxy Of Ge On GaAs For Minority-Carrier Lifetime

MRS Proceedings ◽

10.1557/proc-198-253 ◽

1990 ◽

Vol 198 ◽

Cited By ~ 1

Author(s):

R. Venkatasubramanian ◽

M.L. Timmons ◽

S. Bothra ◽

J.M. Borrego

Keyword(s):

High Temperature ◽

Buffer Layer ◽

Gaas Substrate ◽

Carrier Lifetime ◽

Minority Carrier ◽

High Growth ◽

Minority Carrier Lifetime ◽

Layer Growth ◽

Buffer Layers ◽

Temperature Growth

ABSTRACTGrowth of Ge on GaAs at reasonably high temperatures, which produce better crystallinity in the Ge, presents serious difficulties due to the dissociation of the GaAs substrate. In this paper, we describe the growth of a lowtemperature buffer layer of Ge on GaAs that prevents decomposition of the GaAs during high-temperature growth of Ge. Using this approach, we present the first report of highly specular, mass-transport-limited high-temperature growth of Ge on GaAs that is comparable to the homoepitaxy of Ge. The factors affecting the minority-carrier lifetime of Ge on GaAs, using such an epitaxial growth technique, were studied with a non-invasive microwave technique. Lifetime variations, from very low values to about 0.45 μsec, were obtained as a function of the growth conditions. Significantly, the removal of the surface oxide on the GaAs substrate prior to low-temperature buffer-layer growth, terminating the flow of germane(GeH4) during the ramp to high growth temperatures, thinner buffer layers, and high-temperature growth of Ge were found to be important for obtaining long lifetimes.

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