半绝缘LEC-InP中Fe杂质浓度的分布均匀性

Distribution Uniformity of Fe Impurity Concentration in Semi-Insulating LEC-InP

采用快速原位磷注入法合成InP熔体,采用液封直拉(LEC)法生长了掺Fe半绝缘InP单晶。利用光荧光谱技术、近红外吸收测量和非接触式电阻率测试系统研究了晶体中Fe杂质的分布特性。测试结果表明,在垂直晶锭生长方向切下的(100)InP晶片中,Fe杂质浓度分布一般呈环状,从样品中心部位到边缘部位Fe杂质浓度逐渐升高,这是由于晶体拉制过程中,固液界面为凸向熔体形状所致。但在有些(100)InP样品中,Fe杂质浓度呈条状分布。这种条状的Fe杂质浓度分布特征与晶体生长过程中熔体的对流形成的涡胞形状和涡流方向有关。因此,固液界面并不是影响Fe杂质浓度分布的唯一因素,熔体中涡流对Fe杂质浓度分布的影响是拉制掺Fe InP单晶工艺中需要考虑的重要因素之一。

A rapid in-situ phosphorus injection method was used to synthesize InP melt, and the liquid encapsulated Czochralski(LEC) method was used to grow Fe-doped semi-insulating InP single crystal. The distribution characteristics of Fe impurity in the crystal were investigated by using photoluminescence mapping technology, near infrared absorption measurement and non-contact resistivity test system. The experimental results indicate that in(100) InP wafers cut perpendicular to the growth direction of the ingot, the distribution of Fe impurity concentration generally has a ring shape, which gradually increases from the center to the edge of the sample. It is caused by the convex shape of the solid-liquid interface during the growth process of the crystal. However, in some(100) InP samples, the Fe impurity concentration is distributed in strips. The strip-shaped Fe impurity concentration distribution characteristic is related to the shape and direction of the vortex formed by the convection of the melt during crystal growth. Therefore,the solid-liquid interface is not the only factor affecting Fe impurity concentration distribution. The influence of vortex in the melt on the distribution of Fe impurity concentration is an important factor to be considered in the process of growing Fe-doped InP single crystals.