用范德保法测量碳化硅的电阻率和霍耳效应

应用范德保法测量了电阻率在10^-3—10²欧姆·厘米范围的n型和p型碳化硅单晶和外延层的电学性质。进行了测定条件的选择,范德保法与普通法的对照等试验。发现接触电阻的大小和稳定程度对测量结果有极大的影响。在铟、紫铜、锡、磷铜等机械接触中,铟电极具有最低的接触电阻,其他电极须经电冶成方能进行测定。在不同的电极材料和样品电流下,电阻率偏离约2%,指出,样品电流应当根据具体样品的电阻率和接触电阻加以选择。与普通法比较,范德保法精确度高,数据重复性好。测量了自室温至1000°K范围内碳化硅单晶的高温电学性质,求得氮施主的电离能为0.056电子伏。讨论了引起实验误差的一些异常现象及其产生原因。

MEASUREMENTS OF RESISTIVITY AND HALL EFFECT IN SILICON CARBIDE BY THE VAN DER PAUW METHOD

Measurements of electrical properties using the Van der Pauw technique have been made on the n-type and p-type silicon carbide single crystals and epitaxial layer having resistivity from 10^-3 to 10² ohm-cm. Experiments on the selection of measuring conditions and comparison between the Van der Pauw method and the conventional method have been performed. It is found that the magnitude and stability of contact resistance greatly affect the measuring results. Among the pressure contacts studied, indium contact has the lowest contact resistance, while copper, tin, and phosphor-bronze contacts must be electrically formed before use. With different electrode materials and sample currents, the deviation of values obtained is about 2%. It is suggested that the sample current should be chosen in accordance with the resistivity and contact resistance of the specific sample. As compared with the conventional method, the Van der Pauw method can give higher precision and reproducibility. High temperature electrical properties of silicon carbide single crystals have been measured in a temperature range from room temperature to 1000°K, and the ionization energy of nitrogen donors is found to be 0.056 eV. Anomalous phenomena that result in experimental errors and their origins are discussed.