Metallorganic Vapor Phase Epitaxy Research Articles

Correlation of optical spectra and atomic scale structure of [formula omitted] quantum wells

The impact of the atomic scale structure of the interfaces of AlInAs GaInAs quantum wells grown by atmospheric pressure metallorganic vapor phase epitaxy upon absorption and emission spectra is studied in detail. The results of low temperature calorimetric absorption and variable temperature photoluminescence studies are compared to the results of room temperature high resolution transmission electron microscopy experiments. For the first time the lineshapes of both, luminescence and absorption spectra are fitted with the help of a model using consistent sets of parameters taking into account the real interface structure as well as alloy fluctuations and bandfilling. Average well widths, well width variations and interface roughness are determined. The first reported correlation of direct TEM measurements of the detailed atomic scale structure of QW's with optical spectra does not only remove ambiquities in the interpretation of both types of experiments. More importantly a complete picture of the spectral broadening mechanisms in these ternary alloy samples is obtained and the size of growth islands is estimated. Alloy disorder (clustering) and bandfilling effects are found to dominate spectral broadening.

GaAs MESFET's with Ga1-xAlxAs buffer layers

MESFET's were fabricated with GaAs active layers and Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> As buffer layers grown by metallorganic vapor-phase epitaxy on semi-insulating substrate Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> AS buffer layers with x = 0.2, 0.4, and 0.6 were used to determine the effect of buffer-layer composition on device performance. While very high transconductance values (175 mS/mm) were obtained with buffer layers with x = 0.2, the transconductance decreased with increase of aluminum composition in the buffer layer. The decrease in transconductance may be due to an observed reduction of electron mobility in the active layer with increasing aluminum concentration in the buffer layer.

The growth of a GaP epilayer on Si substrates by metallorganic CVD

Single crystal GaP epilayers can be grown successfully by metallorganic vapour phase epitaxy on Si substrates by thermal decomposition of a gas mixture of triethylgallium (TEG) and phosphine (PH3). The optimum growth temperature and the optimum mole ratio of P and Ga were 660 degrees C and 13 to 1, respectively. The as-grown GaP layer was n-type. The concentration and mobility of GaP layers at room temperature were in the range 3*1016-8.5*1016 cm-3 and 50-100 cm2 V-1 s-1, respectively. I-V and C-V characteristics of this heterojunction device were measured. The leakage current was a few tenths of a mu A and the breakdown voltage was 12 V. A linear relationship of C-2.08 and voltage can be obtained. There is a wide wavelength range of photo-response (from 0.5 mu m to 1.2 mu m) for this diode. The dependence of open-circuit voltage and short-circuit current on light intensity were also measured.