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Dissolution and Growth of InGaSb Ternary Semiconductor under Microgravity

微重力下InGaSb三元半导体的溶解与生长

基本信息

批准号：
11694144
负责人：
KUMAGAWA Masashi
金额：
$ 5.44万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

We have conducted different types of experiments to obtain information on dissolution and growth of InGaSb ternary semiconductor under microgravity and on earth.(1) The microgravity experiment performed in the Chinese recoverable satellite and the reference experiment on earth.(a) the Ga compositional profile of the space-processed sample was uniform in the radial direction, and the interfaces were almost parallel. On the contrary, the larger amount of Ga composition was incorporated in the upper region of the earth-processed sample, and the dissolved zone broadened towards gravitational direction. Numerical simulation results suggested that the GaSb compositional profile in the solution and solution/crystal interface was significantly affected by solutal convection due to compositional difference ; (b) the GaSb with the (111)B plane dissolved into the InSb melt much more than that with the (111)A plane.(2) Experiments performed using an airplane,Crystallization studies were done at a … More reduced gravity level of 10^<-2>G using an airplane (flying in a parabolic trajectory) and at normal gravity conditions on earth. During the crystallization of InGaSb under reduced gravity, there were many needle crystals formed. Though different sizes of these needle crystals formed, most of these crystals were relatively large sized. At the same time, most of the needle crystals resulted during the crystallization process done on earth were considerably smaller in size when compared with the crystals resulted in the reduced gravity condition.(3) Experiments using a drop tower,(a) During the crystallization of InGaSb, many spherical projections were observed on the surface of the sample. The projections emerged out during the crystallization of InGaSb from its melt due to the reason that the density of InGaSb liquid is larger than that of solid.(b) The observed projections were found to be similar to the projections observed in the melting and solidification experiment on In/GaSb/Sb done in IML-2. The projections formed under microgravity were almost spherical, whereas, the projection formed under normal gravity was not perfectly spherical. Due to gravitational pull, the top surface of the projection tended to become flat. This showed the influence of gravity on the formation of projections.(c) The In composition of the crystallized InGaSb varied depending on the existing temperature at the time of formation. This was in accordance with the InSb-GaSb ternary phase diagram.(4) Uni-directional solidification under a temperature gradient(a) When the Seed temperature, the heating rate, the holding period, and the cooling rate were fixed at 648 ℃, 20 ℃/min, 40 h, and 0.5 ℃/min, respectively, the length of the crystal portion with uniform In compositional ratio became longer as the temperature was increased from 1.3 ℃/cm to 9.8 ℃/cm.(b) The crystal length with uniform In compositional ratio became longer with the decrease of cooling rate and the initial In compositions.(c) The dissolved area decreased with the increase of heating rate.(d) The shapes of the dissolved region depend on the gravitational direction. They were perpendicular against the gravitational direction for the horizontal furnace, and broadened towards the gravitational direction in the case of the vertical furnace and the inclined furnace.(5) Numerical simulation on solute transportation as functions of gravity level and g-jitter.Numerical simulations on the flow and compositional distribution in the solution were performed as the analytical backup for the experimental studies.(a) Under zero gravity, as there is no flow, dissolved GaSb diffuses from the interface towards a region far from the interface in the solution. This brings about the compositional gradient along the axial direction in the solution, but the Ga composition is uniform along the radial direction. Therefore, the dissolution of GaSb takes place uniformly at the interface. This results in the flat interface. On the contrary, under normal gravity, the Ga composition is not homogeneous in the radial direction. From the stream lines, it can be understood that a high velocity region exists near the solid-liquid interface. This is because a large amount of Ga-rich solution moves to the upper region due to buoyancy as the density of liquid GaSb (6.01 g/cm^3) is smaller than that of liquid InSb (6.32 g/cm^3). This concentrational gradient becomes a driving force of flow at the interface. At the solid-liquid interface, the dissolution of GaSb in the upper region is suppressed as large amount of Ga composition exists in the upper region of the solution. On the other hand, in the lower region of the solution, a large amount of In composition exists. This increases the dissolution of GaSb into the solution to satisfy the binary InSb-GaSb phase diagram. As a result, the shape of solid-liquid interface broadens towards the bottom. These numerical results can qualitatively explain the experimental results.(b) The flow vector becomes smaller as the gravity level decreases. The shape of the interface becomes parallel with the decrease of gravity levels. With the increase of heating rate in the furnace, the dissolved amount decreases.(c) The effect of g-jitter on the convection increases as the frequency decreases.(d) Thermal Marangoni convection enhances the melting near the free surface under both normal and zero gravity conditions. Under the normal gravity field, the contribution of the solutal Marangoni convection to the flow is less than that of the thermal Marangoni convection because of gravitational segregation. Under zero gravity filed, the inteface shape is greatly affected by both the presence of thermal and solutal Marangoni convections. Less

我们进行了不同类型的实验，以获得在微重力和地球上的InGaSb三元半导体的溶解和生长的信息。(1)中国返回式卫星微重力实验和地球参考实验。(a)空间处理样品的Ga组分分布在径向上是均匀的，界面几乎是平行的。相反，大量的Ga组分被纳入土处理样品的上部区域，溶解带向重力方向加宽。数值模拟结果表明，由于组分的差异，溶液和溶液/晶体界面中的GaSb组分分布受溶质对流的影响显著;（B）具有（111）B晶面的GaSb比具有（111）A晶面的GaSb更多地溶解到InSb熔体中。(2)使用飞机进行的实验，结晶研究在 ...更多信息使用<-2>飞机（以抛物线轨迹飞行）和在地球上的正常重力条件下降低10^ G的重力水平。在InGaSb的失重结晶过程中，有许多针状晶体形成。虽然这些针状晶体大小不一，但大多数都是相对较大的晶体。与此同时，在地球上进行的结晶过程中产生的大多数针状晶体与重力降低条件下产生的晶体相比，尺寸要小得多。(3)使用落塔的实验。（a）在InGaSb的结晶过程中，在样品表面上观察到许多球形突起。由于InGaSb液态密度大于固态密度，在熔体晶化过程中会出现凸起。(b)发现观察到的投影与在IML-2中进行的In/GaSb/Sb熔化和凝固实验中观察到的投影相似。在微重力下形成的突起几乎是球形的，而在正常重力下形成的突起不是完美的球形。由于重力的作用，投影的顶面趋于平坦。这表明重力对投影形成的影响。(c)结晶的InGaSb的In组成根据形成时的存在温度而变化。这与InSb-GaSb三元相图一致。(4)温度梯度下的单向凝固（a）当晶种温度、加热速率、保温时间和冷却速率分别固定为648 ℃、20 ℃/min、40 h和0.5 ℃/min时，随着温度从1.3 ℃/cm增加到9.8 ℃/cm，具有均匀In组分比的晶体部分的长度变长。(b)In组分比均匀的晶体长度随冷却速率和初始In组分的降低而变长。(c)溶解面积随升温速率的增大而减小。(d)溶解区域的形状取决于重力方向。对于卧式炉，它们垂直于重力方向，而对于立式炉和倾斜炉，它们朝着重力方向变宽。(5)数值模拟溶质运移随重力水平和g-抖动的变化，数值模拟溶液中的流动和组分分布，作为实验研究的分析支持。(a)在零重力下，由于没有流动，溶解的GaSb从界面向溶液中远离界面的区域扩散。这导致溶液中的组分沿着轴向梯度，但Ga组分沿沿着是均匀的。因此，GaSb的溶解均匀地发生在界面处。这导致平坦界面。在正常重力作用下，Ga组分在径向上是不均匀的.从流线可以理解，在固液界面附近存在高速区域。这是因为液体GaSb的密度（6.01 g/cm^3）比液体InSb的密度（6.32 g/cm^3）小，所以大量的富Ga溶液由于浮力而移动到上部区域。这种浓度梯度成为界面处流动的驱动力。在固-液界面处，由于溶液上部区域存在大量的Ga组分，抑制了上部区域中GaSb的溶解。另一方面，在溶液的下部区域中，存在大量的In成分。这增加了GaSb到溶液中的溶解以满足二元InSb-GaSb相图。结果，固液界面的形状向底部加宽。这些数值结果可以定性地解释实验结果。(b)随着重力水平的降低，流动矢量变小。界面的形状随着重力水平的降低而变得平行。随着炉内升温速率的增加，溶解量减少。(c)g抖动对对流的影响随着频率的降低而增加。(d)热Marangoni对流增强正常和零重力条件下的自由表面附近的熔化。在正常重力场作用下，由于重力分凝作用，溶质Marangoni对流对流动的贡献小于热Marangoni对流。在失重条件下，热Marangoni对流和溶质Marangoni对流的存在对界面形状有很大的影响。少