(463g) The Chemical Vapor Deposition Growth of Gallium Arsenide-Based Quantum Well ‘W' Structures for Mid-IR | AIChE

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(463g) The Chemical Vapor Deposition Growth of Gallium Arsenide-Based Quantum Well ‘W' Structures for Mid-IR

Authors 

Rathi, M. - Presenter, University of Wisconsin
Khandekar, A. A. - Presenter, University of Wisconsin
Xu, D. - Presenter, University of Wisconsin
Huang, J. Y. T. - Presenter, University of Wisconsin
Mawst, L. J. - Presenter, University of Wisconsin
Park, J. - Presenter, University of Wisconsin
Song, X. - Presenter, University of Wisconsin
Babcock, S. - Presenter, University of Wisconsin


The conventional active region for achieving 1.55 μm
wavelength operation is based on InGaAs- or InGaAsP-based multiple quantum
wells (MQWs) on InP substrates. GaAs1-ySby-GaAs1-zNz
type-II quantum well (QW) active regions hold potential for fabrication of 1.55
μm diode lasers on GaAs substrate. The lasing performance of InP-based vertical
cavity surface emitting lasers (VCSELs) is inferior to that of GaAs-based VCSELs.
Devices based on GaAs1-ySby-GaAs1-zNz
should exhibit improved temperature insensitivity due to large band offsets between
GaAs1-ySby and GaAs1-yNy. Strong
overlap between electron-hole wavefunctions determines the differential gain of
a lasing device. For mid-infrared range applications, the ?W' structure is
widely accepted, where a hole QW is sandwiched between two electron QWs that
provides large wavefunction overlap. From k·p simulations, an antimony mole
fraction of 0.35 to 0.4 in the GaAs1-ySby hole well layer
and an nitrogen mole fraction of 0.01 to 0.015 in the GaAs1-yNy
electron well layer are desired for strong carrier confinement and long
emission wavelength. The broad miscibility gap between GaAs1-ySby
and GaAs1-zNz prevents formation of a homogeneous alloy
over the entire range of desired composition under conditions of thermodynamic
equilibrium. Triethyl gallium, trimethyl antimony, dimethyl hydrazine and
arsine are used as precursors in metal-organic vapor phase epitaxy (MOVPE) to
grow GaAs1-ySby and GaAs1-zNz. As/III
ratio in the gas phase affects the antimony incorporation in the solid film
significantly. X-ray diffraction (XRD) as well as electron probe microanalysis
(EPMA) techniques are used to determine the composition in the thin films.
Abrupt interfaces between the thin layers of GaAs1-ySby
and GaAs1-zNz are essential for device performance.
Formation of an antimony segregation layer and possible arsenic-for-antimony
exchange processes lead to interfacial grading and low antimony incorporation
in thin layers. Gas switching sequences and optimization to achieve abrupt
interfaces will be discussed. Samples were grown containing 3 ?W' structured GaAs1-ySby
- GaAs1-zNz layers, each separated by a GaAs layer and cladded
by Al0.7Ga0.3As barriers on both ends. These samples were
annealed under arsine at 650oC to remove probable nitrogen clustering.
The photoluminescence (PL) results from these samples before and after
annealing are compared.  Annealing results in an increase in the intensity and
a blue shift in the emission wavelength. The highest emission wavelength, 1457
nm, is achieved to date using a 3 nm GaAs0.6Sb0.4 and 2
nm GaAs0.988N0.012 ?W' structure.

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