一步热压法制备N型Si80Ge20及其热电性能

Preparation and Thermoelectric Properties of N-type Si80Ge20 by One-step Hot Pressing Method

采用一步热压法制备了N型Si80Ge20Px(x=0.2、1.0、2.0),通过改变P掺杂优化载流子浓度,对样品进行物相分析与微观结构分析,测试并比较了样品在30~800℃下的热电参数。结果表明:一步热压法可实现硅锗固相反应合金化,制备的Si80Ge20结构致密、组分均匀;随着P掺杂增加,Si80Ge20Px的电导率增加,Seebeck系数降低,功率因子增加,热导率变化不明显,ZT值增加;在30~800℃,Si80Ge20P0.2的功率因子和ZT值随温度升高先增加后降低,在700℃达到最大值,Si80Ge20P1.0和Si80Ge20P2.0的功率因子和ZT值随温度升高而增加,其中Si80Ge20P2.0在800℃时功率因子为3.0 mW/(m·K2),ZT值0.78。该方法工艺简单,可精确控制P的掺杂,通过载流子浓度优化可获得性能较佳的N型Si80Ge20。

N-typeSi80Ge20Px(x=0.2,1.0,2.0)was prepared by one-step hot pressing method,and the carrier concentration was optimized by changing the P doping.Phase analysis and microstructure analysis were conducted on the samples,and the thermoelectric properties of each sample were tested and compared.The results show that one-step hot pressing method can realize the solid-phase reaction alloying of silicon germanium,and the Si80Ge20 has a dense structure and uniform composition;With the increase of P doping in Si80Ge20Px,the conductivity increases,the Seebeck coefficient decreases,the power factor increases,the thermal conductivity does not change significantly,and the ZT value increases;Within 30—800℃,the power factor and ZT value of Si80Ge20P0.2 first increase and then decrease with the increase of temperature,and reach the maximum at 700℃.The power factor and ZT value of Si80Ge20P1.0 and Si80Ge20P2.0 increase with the increase of temperature.The power factor of Si80Ge20P2.0 is 3.0 mW/(m·K2),and the ZT value is 0.78 at 800℃.The method has a simple process,can accurately control the doping of P,and can obtain an N-type Si80Ge20 with better performance through carrier concentration optimization.