Selective area growth of III-V semiconductors: From fundamental aspects to device structures

Fundamental aspects in the selective-area metal-organic vapor-phase epitaxy (MOVPE) of III-V semiconductors are presented in this paper, with an emphasis on the role of vapor-phase diffusion of a group-III precursor, which plays the dominant role for substantial modulation of an effective bandgap around wider (>100 μm) masks and is a characteristic of MOVPE that is operated close to atmospheric pressure. A single parameter, D/k
_s
(vapor-phase mass diffusivity / surface incorporation rate coefficient), determines modulation of both thickness and composition of a layer. The value of D/k
_s
can be regarded as an effective lateral diffusion length of a group-III precursor, and the value of k
_s
can be decoupled from D/k
_s
, providing insight to surface reaction kinetics of MOVPE. Coupling with reactor-scale distributions provides unique basis for the discussion of comprehensive reaction mechanism. The values of k
_s
will be presented for basic materials composing InGaAsP system. Luminescence wavelength from multiple quantum wells (MQWs) around a given mask pattern can be simulated precisely based on a simple diffusion/reaction model and it is applicable to monolithic integration of devices using selective-area growth of InGaAsP-related materials. The same framework can be applied to III-nitride materials, and k
_s
values for GaN growth have been obtained. Visible luminescence from InGaN/GaN MQWs on a patterned GaN template was red-shifted according to the mask width, for which only the thickness modulation of the InGaN wells has been suggested to be the governing mechanism.