Thickness Uniformity of GaAs Layers Grown by Electroepitaxy

Abstract

The thickness profiles of GaAs layers grown by electroepitaxy (currentcontrolled liquid phase epitaxy) were investigated in conjunction with experimental growth parameters. It was found that defective electrical contacts to the substrate and variations in the dissolution depth of the substrate by the gallium contact layer lead to random fluctuations in the epitaxial layers. Convective flow in the solution due to horizontal gradients in the solution caused by joule heating leads to systematic variations in the thickness of the epilayers. Experimental procedures are presented for mlmzmzlng or essentially eliminating both types of thickness variations.Current-controlled liquid phase epitaxy, referred to from here on as electroepitaxy, of semiconductors and * Electrochemical Society Active Member. Permanent address: ECL, Nippon Telegraph and Telephone Publie Corporation, Tokyo, Japan.

Recent developments in modelling of liquid phase electroepitaxy under applied magnetic field

“…The applied electric current is the sole ____________________ driving force for growth, and gives rise to two growth mechanisms that are known as "electromigration' and "Peltier cooling/heating". The electromigration of species in the liquid solution is believed to take place due to electron-momentum exchange and electrostatic field forces, and sustains a controlled-growth [18,19]. The Peltier heating/cooling, on the other hand, is a thermoelectric effect occurring when an electric current passes through an interface of two materials with different Peltier coefficients.…”

“…For instance, the growth furnace temperatures used are relatively low, the temperature gradients in the LPEE system are very low, maximum in the order of a few °C/cm, LPEE has the ability of well-controlled growth, by simply controlling the applied electric current, and ternary single crystals can be grown with uniform compositions. Such features of LPEE make this technique technologically very promising (see for instance [18][19][20][21][22][23][24][25][26][27][28]), and it has a great potential to become a commercial technique in growing high quality, bulk crystals such as GaInAs, GaInSb, CdZnTe, and SiGe (see Refs. [10,11,23,25,27]).…”

Numerical analysis of growth kinetics of bulk III‐V crystals grown by liquid phase electroepitaxy

“…At the liquid solution-crystal interface, the Peltier effect is accounted in the boundary condition for temperature by direct contribution to the heat balance equation [11,12]:…”

On the high growth rates in electroepitaxial growth of bulk semiconductor crystals in magnetic field

“…In LPEE, growth is achieved by passing an electric current through the growth cell while the overall furnace temperature is kept constant during the entire growth period. The applied electric current is the sole driving force for growth, and gives rise to the electromigration of species in the liquid solution that sustains a controlled-growth [1][2][3][4]. Although the furnace temperature is constant in LPEE, the combined effect of the Joule heating in the solid crystals and the Peltier heating/cooling at the liquid/solid interfaces leads to relatively strong convection in the solution.…”

“…[1][2][3][4]). In addition, the presence of an applied magnetic field in LPEE increases the mass transport in the liquid solution tremendously; leading to flat and thick crystals with very high growth rates [14,15].…”