Ga-rich Solutions Research Articles

Gallium antimonide LPE growth from Ga-rich and Sh-rich solutions

Epitaxial layers of undoped p-GaSb were grown from Ga-rich and Sb-rich solutions on (111) and (100) oriented GaSb substrates. The growth temperatures ranged from 330–470°C (Ga solution) and 635–680°C (Sb solution). Different growth results were obtained for the two LPE processes. The layers were characterized by photoluminescence measurements at low temperatures (1.8 K). The highest purity was obtained by low temperature LPE from Ga solutions.

Gallium antimonide LPE growth from Ga-rich and Sb-rich solutions

Gallium antimonide LPE growth from Ga-rich and Sb-rich solutions

Sharp coupling transition of Gd in AlGa solvents

We report NMR and susceptibility measurements on liquid AlGa alloys doped with Gd impurities. Results for the AlGa host alloys show that the solvents form an almost ideal isovalent free-electron-like series of alloys. The coupling of Gd $4f$ cores to the conduction band, as revealed by the ${\mathrm{Al}}^{27}$, ${\mathrm{Ga}}^{69}$, and ${\mathrm{Ga}}^{71}$ Knight shifts, nevertheless exhibits an abrupt transition from strong coupling in Al-rich hosts to very weak coupling for Ga-rich solutions. This takes place with no marked change in the impurity susceptibility. The transition occurs at 96-at.% Al, and is much sharper than similar transitions previously reported for Gd and Ho in Al-noble-metal liquid hosts. Neither the structure of the strong-coupling configuration nor the mechanism of the transition can as yet be established definitively.

Phase equilibria and vapor pressures in the Ga + P system

Compositions and vapor pressures have been redetermined along the Ga-rich liquidus of the system Ga + P. A third-law treatment of the pressures gives a standard enthalpy ΔH o(298.15 K) = −(45.3 ± 0.2) kcal th mol −1 and a standard entropy ΔS o(298.15 K) = −(23.7 ± 0.15) cal thK −1mol −1 for the reaction Ga(s) + 1 2 P 2(g) = GaP(s) . The standard enthalpy of formation and entropy of GaP are ΔH f o (GaP,s,298.15 K) = −(24.0 ± 0.5) kcal thmol −1 and S o(GaP,s,298.15 K) = (12.10 ± 0.25) cal thK −1mol −1. The activities of phosphorus are evaluated along the liquidus and indicate that the deviations from ideality in the Ga-rich solutions results primarily from a small positive excess entropy of mixing. A self-consistent analysis of the liquid- and vapor-phase equilibria based on a simple solution treatment of the Ga + P liquid is presented.

A new rotating-boat technique for liquid phase epitaxial growth of gallium arsenide

A new technique has been developed to avoid constitutional supercooling in the growth of gallium arsenide by liquid phase epitaxy from an unconfined Ga-rich solution. This technique utilises a graphite boat that permits the growth solution to be initially saturated with GaAs at a temperature significantly higher than the substrate temperature. The boat is rotated to bring the solution into contact with the substrate, and rotated again to decant the solution after the growth is completed. If the initial temperature difference between the solution and the substrate is high enough, constitutional supercooling does not occur, and this procedure yields epitaxial layers with smooth surfaces free of cellular structure.

Growth of GaAs 1− xP x crystals by pulling from gallium-rich solutions

GaAs 1− x P x was grown by pulling from Ga-rich solutions using the liquid encapsulation method. X-ray analysis and optical measurements performed on the first grown portion of the crystal give a value x=0.3. Electrical measurements showed that the crystal is n-type with carrier concentration N = ∼ 10 17 cm −3 and Hall mobilities μ H = ∼ 500 cm 2 V −1 sec −1 at room temperature.

Calcul des conditions de croissance de cristaux en solution

The mass balance integral method is used to determine the transient growth rate and the critical the mal gradient for diffusion mass transport solution growth. Two general methods of growing crystals were studied. 1.(1) Growth of thick crystals by controlled displacement of the presupposed crystal-solution equilibrium at the interface: The theoretical result was applied to cadmium-rich solution growth of CdTe crystals. The rate shows a maximum for relatively short time before a slowly decreasing variation take place. The critical thermal gradient shows a continuously increasing variation with time.2.(2) Liquid phase epitaxy under transient thermal conditions: This method was used by R.H. Deitch for the growth of GaAs layer in Ga rich solution. The experimental results allow the numerical adjustment of two unknown parameters: the “thermal” parameters which depend on the experimental conditions and the arsenic liquid diffusion coefficient. The latter one has too low a value showing that interfacial phenomenon kinetics slow down the rate of growth and must be taken into account in theoretical treatment.

Acceptor behaviour of germanium in gallium arsenide

Acceptor behaviour of Ge doped GaAs grown from Ga rich solution is studied. An ionization energy of the acceptor level of 43 meV at 10 17 cm −3 hole density and the segregation coefficient of 1.2 × 10 −2 are determined.