Spectroscopic Ellipsometric Characterization of Low Temperature GaAs

AbstractPseudodielectric functions of low temperature grown GaAs (LT GaAs) measured by spectroscopic ellipsometry are presented. The spectral range includes the El (2.92eV) and El+ΔAl (3.13eV) critical point structure of GaAs. A Lorentz-oscillator model was used to fit the dielectric function of LT GaAs for samples with nominal growth temperatures (Tg) varying from 200°C to 580°C. For Tg of 200°C, 30% and 19% broadenings and −0.01 leV and −0.007eV red shifts were found for the El and El+Δl structures respectively, compared with normal GaAs. The red shift can be explained in terms of a strain effect in the LT layer. In annealed LT GaAs the broadening decreased significantly and no red shift was found.

Download Full-text

Study of Modulation in GaAs Misfets with LT-GaAs as a Gate Insulator

MRS Proceedings ◽

10.1557/proc-241-181 ◽

1991 ◽

Vol 241 ◽

Cited By ~ 4

Author(s):

L.-W. Yin ◽

J. Ibbetson ◽

M. M. Hashemi ◽

W. Jiang ◽

S.-Y. Hu ◽

...

Keyword(s):

Low Temperature ◽

Gaas Layer ◽

Gate Insulator ◽

Gate Bias ◽

Channel Current ◽

Turn On ◽

Dc Characteristics ◽

Low Temperature Gaas ◽

Channel Separation ◽

Lt Gaas

ABSTRACTDC characteristics of a GaAs MISFET structure using low-temperature GaAs (LTGaAs) as the gate insulator were investigated. MISFETs with different gate to channel separation (d) were fabricated. The dependence of four important device parameters such as gate-drain breakdown voltage (VBR), channel current at zero gate bias (Idss), transconductance (gm), and gate-drain turn-on voltage (Von) on the gate insulator thickness were analyzed. It was observed that (a) in terms of Idss and gin, the LT-GaAs gate insulator behaves like an undoped regular GaAs layer and (b) in terms of VBR and Von, the LT-GaAs gate insulator behaves as a trap dominated layer.

Download Full-text

Electrical Characterization of Low Temperature GaAs Layers, and Observation of the Extremely Large Carrier Concentrations in Undoped Material

MRS Proceedings ◽

10.1557/proc-241-199 ◽

1991 ◽

Vol 241 ◽

Author(s):

Bijan Tadayon ◽

Mohammad Fatemi ◽

Saied Tadayon ◽

F. Moore ◽

Harry Dietrich

Keyword(s):

Molecular Beam Epitaxy ◽

Low Temperature ◽

Substrate Temperature ◽

Molecular Beam ◽

Electrical Characterization ◽

Physical Characteristics ◽

Hall Measurements ◽

Undoped Material ◽

Low Temperature Gaas

ABSTRACTWe present here the results of a study on the effect of substrate temperature, Ts, on the electrical and physical characteristics of low temperature (LT) molecular beam epitaxy GaAs layers. Hall measurements have been performed on the asgrown samples and on samples annealed at 610 °C and 850 °C. Si implantation into these layers has also been investigated.

Download Full-text

Laser Quality AlGaAs-GaAs Quantum Wells Grown on Low Temperature GaAs

MRS Proceedings ◽

10.1557/proc-241-239 ◽

1991 ◽

Vol 241 ◽

Author(s):

Y. Hwang ◽

D. Zhang ◽

T. Zhang ◽

M. Mytych ◽

R. M. Kolbas

Keyword(s):

Molecular Beam Epitaxy ◽

Low Temperature ◽

Quantum Wells ◽

Barrier Layer ◽

Molecular Beam ◽

Optical Quality ◽

First Order ◽

Gaas Buffer Layer ◽

Low Temperature Gaas ◽

Lt Gaas

ABSTRACTIn this work we demonstrate that photopumped quantum wellheterostructure lasers with excellent optical quality can be grown ontop of a LT GaAs buffer layer by molecular beam epitaxy. Hightemperature thermal annealing of these lasers blue-shifts the laseremission wavelengths but the presence/absence of a LT GaAs layerhad little effect on the overall laser thresholds. Also, to first order itwas not necessary to include an AlAs barrier layer to preventadverse effects (as has been necessary in the gate stack of MESFETs to prevent carrier compensation).

Download Full-text

Optical characterization of low temperature grown GaAs by transmission measurements above the band gap

Journal of Vacuum Science & Technology B Microelectronics Processing and Phenomena ◽

10.1116/1.588918 ◽

1996 ◽

Vol 14 (3) ◽

pp. 2275 ◽

Cited By ~ 10

Author(s):

D. Streb

Keyword(s):

Low Temperature ◽

Band Gap ◽

Optical Characterization ◽

Transmission Measurements ◽

Low Temperature Grown Gaas

Download Full-text

Influence of Low Temperature-Grown GaAs on Lateral Thermal Oxidation of Al0.98Ga0.02As

MRS Proceedings ◽

10.1557/proc-623-407 ◽

2000 ◽

Vol 623 ◽

Author(s):

J. C. Ferrer ◽

Z. Liliental-Weber ◽

H. Reese ◽

Y.J. Chiu ◽

E. Hu

Keyword(s):

Low Temperature ◽

Thermal Oxidation ◽

Oxidation Process ◽

Gaas Layer ◽

Transmission Electron ◽

Low Temperature Gaas ◽

Reference Samples ◽

Thermal Oxidation Process ◽

Low Temperature Grown Gaas

AbstractThe lateral thermal oxidation process of Al0.98Ga0.02As layers has been studied by transmission electron microscopy. Growing a low-temperature GaAs layer below the Al0.98Ga0.02As has been shown to result in better quality of the oxide/GaAs interfaces compared to reference samples. While the later have As precipitation above and below the oxide layer and roughness and voids at the oxide/GaAs interface, the structures with low-temperature have less As precipitation and develop interfaces without voids. These results are explained in terms of the diffusion of the As toward the low temperature layer. The effect of the addition of a Si02 cap layer is also discussed.

Download Full-text

Real-Time Pseudodielectric Function of Low-Temperature-Grown GaAs

MRS Proceedings ◽

10.1557/proc-618-243 ◽

2000 ◽

Vol 618 ◽

Author(s):

D.A. Gajewski ◽

J.E. Guyer ◽

J.J. Kopanski ◽

J.G. Pellegrino

Keyword(s):

Low Temperature ◽

Real Time ◽

Diffuse Reflectance Spectroscopy ◽

High Energy ◽

Real Time Control ◽

The Real ◽

Time Control ◽

Active Feedback ◽

Low Temperature Grown Gaas ◽

Lt Gaas

ABSTRACTWe present the real-time pseudodielectric function <ε(E)> of low-temperature-grown GaAs (LT-GaAs) thin films during the growth as a function of growth temperature Tg and thickness. We obtained accurate measurements of the real-time <εc(E)> by using in situspectroscopic ellipsometry (SE) in conjunction with active feedback control of the substrate temperature using diffuse reflectance spectroscopy. We show that for epitaxial LT-GaAs layers, the peak in the imaginary pseudodielectric function <ε2(E)> decreases in amplitude and sharpness systematically with decreasing Tg. We also revealed an abrupt change in <εc(E)> near the critical epitaxial thickness hepi, the value of which decreases with decreasing Tg. Above hepi, the LT-GaAs grows polycrystalline (amorphous) above (below) Tg ∼ 190°C. We also simultaneously monitored the surface roughness and crystallinity by using real-time reflection high-energy electron diffraction (RHEED). These results represent progress in obtaining real-time control over the composition and morphology of LT-GaAs

Download Full-text

Multi-Hundred Gigahertz Photodetector Development Using LT GaAs

MRS Proceedings ◽

10.1557/proc-241-227 ◽

1991 ◽

Vol 241 ◽

Author(s):

Y. Chen ◽

S. Williamson ◽

T. Brock ◽

F. W. Smith ◽

A. R. Calawa

Keyword(s):

Low Temperature ◽

Light Intensity ◽

Response Time ◽

Bias Voltage ◽

Type Detector ◽

Low Temperature Grown Gaas ◽

Lt Gaas

ABSTRACTWe report on the development of a new, integrable photoconductive-type detector based on low-temperature-grown GaAs. The detector has a response time of 1.2 ps and a 3-dB bandwidth of 375 GHz. The responsivity is 0.1 A/W. This is the fastest photodetector reported to date. We discuss the unique properties of this device, including its performance as functions of both light intensity and bias voltage.

Download Full-text