A thermodynamical model of molecular beam epitaxy, application to the growth of II VI semiconductors
We present a model of molecular beam epitaxy based on thermodynamics. The equilibrium between a compound or a ternary alloy with the gas phase is illustrated in the case of HgTe and CdHgTe. The meaning of equilibrium pressure is analysed and we make the assumption that the fluxes leaving the actual growing compound are linked by the mass action law where the pressures are transformed into the equivalent fluxes. A detailed balance of the species leaving or arriving at the surface is then possible and leads to a set of equations which can be solved to predict the growth rate, the x value of a ternary alloy, the excess of one of the species, the incorporation coefficient. Examples of calculation are shown for CdTe and Cd x Hg 1−x Te and are compared with experimental results and show a good agreement. The main interest of this model resides in its ability to predict the effects of the modification of one of the growth parameter. Nevertheless it predicts only the limit conditions which are not necessary reach due to the kinetic of the reactions Presentation d'un modele thermodynamique de l'epitaxie par jets moleculaires. Illustration par les cas de HgTe et CdHgTe. La comparaison avec les resultats experimentaux montre la validite des previsions du modele, dont l'interet principal est de permettre d'evaluer l'influence de la modification d'un parametre de croissance. La validite de ce modele est cependant limitee si la cinetique des reactions ne permet pas d'atteindre l'equilibre; ce n'est pas le cas pour les alliages II-VI etudies ici
Germanium doping of gallium arsenide grown by molecular beam epitaxy — Some thermodynamic aspects
Abstract A recent point defect model for GaAs, developed by Hurle to explain results from vapour phase and liquid phase epitaxy, has been extrapolated to apply to molecular beam epitaxy (MBE). Particular attention has been paid to the amphoteric doping obtained using Ge in MBE growth of GaAs. This thermodynamic treatment is shown to explain all the major features of recent experimental results. Thus, despite important non-equilibrium aspects of MBE growth, it appears that equilibrium thermodynamics can be used as a satisfactory guide to majority carrier dopant behaviour even in this complex case. An important supplementary result of the treatment is that As 2 should be a preferable source of arsenic to As 4 in MBE growth of GaAs.
Properties of Liquid Phase Epitaxial Ge-Doped GaAs
The incorporation of Ge into liquid phase epitaxial GaAs is investigated as a function of the growth temperature (725 to 1025 °C), the substrate orientation ((111) A, (111) B), and the mole fraction x of Ge in the liquid phase (0.2 to 20 at%) The Ge content in the solid phase depends linearly on x and increases slightly with rising growth temperature. No influence of the substrate orientation on the incorporation of Ge is found. 
 
 
 
Der Einbau von Ge in durch Flussigphasenepitaxie gezuchtetes GaAs wird als Funktion der Zuchtungstemperatur (725 bis 1025 °C), der Substratorientierung ((111) A, (111) B) und des Molenbruchs x des Ge in der flussigen Phase (0,2 bis 20 at%) untersucht. Der Ge-Gehalt in der festen Phase hangt linear von x ab und steigt mit wachsender Zuchtungstemperatur leicht an. Es wird kein Einflus der Substratorientierung auf den Ge-Einbau gefunden.