The investigation of P‐ and As diffusion in liquid Gallium

Abstract

The results on the As-and P-diffusion in gallium melt are discussed. The definition method of P-and As-diffusion coefficients in liquid gallium was stated. This method was based on t h e analysis ofconcentration profile formed during the diffusion annealing with following tempering. The diffusion coefficients were measured on temperature region 11 13 to 1383 K. The expression for temperature dependence of diffusion coefficients was obtained.CHcTeMaX Ga-P II Ga-As. The diffusion mass-transport in the liquid phase is one of the most important factors determining the properties of A3B6 compounds and their solid solutions during the epitaxy process (SMALL and CROSSLEY).The information on diffusion coefficients in the melt is necessary for performing epitaxy under controlled conditions. The aim of the present paper is the description of the diffusion parameters measurements method and also the temperature dependence of diffusion coefficients in the systems Ga-P and Ga-As.There are two methods for determination of diffusion coefficients of phosphorus (DGa) and arsenic (DGa) in gallium melt. The first of them is based on indirect determination of the coefficients from the crystallization rate of semiconductors by KANENKO et al. and BRYSKIEWICZ. The second one is connected with the determination of semiconductors dissolution rate in the unsaturated melt by NEVSKY et al., and VIGDOROVrCH et al. The kinetic processes a t the interphase are not taken into account, whereas their contribution in the mass transport can be compared t o the mass transport in liquid phase. The convective mixing in the melt could also considerably influence the epitaxy crystallization rate (MILVIDSKI et al.).I n the present work the diffusion coefficients were determined directly from impurity (As or P) concentration profile formed after diffusion annealing and following tempering.The quartz capillar of 1.5e2.0 mm in diameter filled with gallium was used as an experimental cell. The impurity source in the form of single crystal (Gap or GaAs) was placed on gallium surface. The mass of the source was taken for the diffusion condition from the infinitely thin layer, Such niodel allows us to eliminate the influence of the processes at the interphase boundary. The vertical situation of the cell in the heater was used during the diffusion annealing. The impurity source was situated in the upper part of the capillar. This allows u s t o minimize the influence of convection mixing of the melt. The melt was undergone to the tempering at the liquid nitrogen temperature. After that the specimen was extracted from the capillar.

Dynamics of mass transport during nanohole drilling by local droplet etching

“…We identify the formation of the crystalline wall around the nanohole opening to be the essential process for As removal [ 38 ]. That means, after removal from the substrate, the As atoms travel very fast through the liquid droplet [ 40 ] and crystallize the wall [ 38 , 41 ] with droplet material at the triple line at the border between the droplet surface and the substrate. This picture is supported by the observation of equal volumes of material stored inside a wall and of material removed from a hole [ 42 ].…”

Unified model of droplet epitaxy for compound semiconductor nanostructures: Experiments and theory

“…Arsenic atoms deposited near or on the droplet diffuse through the liquid quickly 20 and attach most typically near the triple-junction. Such crystallization results in a growing GaAs front and the droplet is crystallized inward.…”

“…The TEM top views of islands from sample A, obtained with diffraction vector g = [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] clearly show Moiré fringes, due to the interference between the crystal lattice of the island (GaAs) and that the Si substrate ( Figure 11). EDS map scans show the same distribution of the Ga and As signals, which mimics the island shape, thus demonstrating the correct stoichiometry of the GaAs all over the island volume -i.e.…”

Механизм роста пар--кристалл--кристалл Au-каталитических GaAs-нитевидных нанокристаллов

“…As exp(−E As /kT ), где D 0 As = 1.59 • 10 −5 м 2 • c −1 , E As = 700 мэВ [49], так что D As ∼ 10 −10 м 2 • c −1 при T ∼ 420 • C. Межфазную поверхностную энергию γ примем равной 0.72 Дж • м −2 [50]. Результаты расчетов показывают, что время нуклеации равно τ N ∼ 1−10 с при рассматриваемых потоках мышьяка, т. е. может быть на несколько порядков больше характерного времени зарождения когерентных островков при твердофазной нуклеации.…”