Investigation of the parameters which control the growth of {111} and {} faces of GaAs by chemical vapour deposit

Design of Planarizing Growth Conditions on Unpolished and Faceted (100)-Oriented GaAs Substrates Using Hydride Vapor Phase Epitaxy

“…Figure diagrams these flows in the reactor used in this study. These gases were chosen because they are known to have a significant effect on the growth rate on fully polished substrates in HVPE and can be used to vary the partial pressure of reactants at the substrate surface, potentially affecting growth kinetics and facilitating planarization. ,,,, The AsH 3 flow rate affects the amount of AsH 3 that reaches the surface, and the flow rate of HCl over the Ga metal source, henceforth referred to as the GaCl flow rate, affects the amount of GaCl that reaches the surface. The AsH 3 carrier flow rate is inversely proportional to the degree of AsH 3 cracking, which affects the effective Group V partial pressure during growth because we operated in the hydride-enhanced growth regime where AsH 3 is the primary active Group V species for growth .…”

“…25,26 The free-HCl flow rate directly affects the amount of HCl at the surface during growth, which can affect the driving force for the growth reaction. 16,27 These five flows were used as five factors in a definitive screening design with 13 experiments, and the known effects of these flow rates on the growth environment were considered in the analysis of the DoE results. Three levels for each factor were chosen as AsH 3 flow rate with 50, 75, and 100 sccm, GaCl flow rate with 5, 10, and 15 sccm, AsH 3 carrier flow rate with 1000, 1750, and 2500 sccm, GaCl carrier flow rate with 250, 750, and 1250 sccm, and free HCl with 4, 7, and 10 sccm.…”

“…The AsH 3 carrier flow rate is inversely proportional to the degree of AsH 3 cracking, which affects the effective Group V partial pressure during growth because we operated in the hydride-enhanced growth regime where AsH 3 is the primary active Group V species for growth . The GaCl carrier flow rate affects the conversion of HCl to GaCl and thus can contribute to changes in both the GaCl and free-HCl partial pressure during growth. , The free-HCl flow rate directly affects the amount of HCl at the surface during growth, which can affect the driving force for the growth reaction. , These five flows were used as five factors in a definitive screening design with 13 experiments, and the known effects of these flow rates on the growth environment were considered in the analysis of the DoE results. Three levels for each factor were chosen as AsH 3 flow rate with 50, 75, and 100 sccm, GaCl flow rate with 5, 10, and 15 sccm, AsH 3 carrier flow rate with 1000, 1750, and 2500 sccm, GaCl carrier flow rate with 250, 750, and 1250 sccm, and free HCl with 4, 7, and 10 sccm.…”

“…Here, we employed hydride vapor phase epitaxy (HVPE), a potentially low-cost III-V growth technique due to its lower-cost precursors, high utilization, and high growth rates (>500 μm/h). ,, The addition of a planarizing growth step will add some additional cost to device growth due to material usage and growth time; however, a high growth rate and potentially low-cost-material growth via HVPE have the potential to minimize these costs. HVPE is also potentially enabling as a planarization technology because of pronounced growth rate anisotropies caused by differences in the kinetic limitations of growth on different crystal planes. − Prior studies show that varying the V/III ratio (ratio between the Group V and Group III precursors) as well as the free-HCl partial pressure enables the growth of differently shaped structures from initially flat surfaces by impacting adsorption energy on different surfaces. − There is little work in applying the effect of growth rate anisotropy to changing the morphology of a surface with a pre-existing non-planar morphology, and the parameter space of growth conditions that enable the anisotropy behavior is large, so an efficient study of the effect of growth flows on growth rate anisotropy in HVPE is needed to determine favorable planarization growth conditions on rough surfaces.…”

Multichamber Reactors : A Solution to the Problem of Graded Heterointerfaces in Hot-Wall Vpe Systems

“…These chemical reactions o n l y degend on t h e concentration o f the reacting ssecies i n the n u t r i e n t phase, on the coverage r a t i o o f the a c t i v e surface, and on adsorption and desoration energies ; k i n e t i c s are u s u a l l y more r a p i d than mass t r a n s f e r during composition changes ; otherwise, they are time-inde~endent, and have been studied by s t a t i s t i c a l ohysics and the theory o f r a t e processes (15)(16)(17).…”