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/ks (vapor-phase mass diffusivity / surface incorporation rate coefficient), determines modulation of both thickness and composition of a layer. The value of D/ks can be regarded as an effective lateral diffusion length of a group-III precursor, and the value of ks can be decoupled from D/ks, 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 ks 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 ks 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.