高电导a-Si:H:Y合金的电输运特性

本文报道由rf溅射技术将稀土元素Y掺入非晶硅,当掺Y浓度为20％左右时,获得了室温直流电导率为2×10¹Ω^-1·cm^-1的a-Si:H:Y合金膜。测量表明该合金膜是n型。变温电导测量指出,在测量温度范围内lnσ与l/T的关系可拟合于两条直线。对于衬底温度为260℃,290℃和330℃溅射的合金膜,其转折点分别出现在～70℃,～75℃和～90℃。这表明a-Si:H:Y合金膜存在两种电传导机制:在室温附近电子在Y施主杂质带内跳跃传导,在高温情况下电子在导带延展态内传导。并且得到Y施主杂质带中心处于导带E_c以下0.06—0.07eV。 关键词：

ELECTRONIC TRANSPORT PROPERTIES OF HIGH CONDUCTIVITY a-Si:H:Y ALLOY

The high conductivity a-Si:H:Y alloy films prepared by rf sputtering have been obtained. The room temperature d.c. conductivity is about 2×10¹ Ω^-1·cm^-1 as Y doping concentration reaches 20 at %. Measurements showed that the alloy films are of n-type. The plots of In a versus 1/T over temperature range investigated can be fitted by two straight lines with a kink occurring at a temperature which is ～70℃, ～75℃ and ～90℃, respectively, for samples deposited at substrate temperature T₂ = 260℃, 290℃ and 330℃. Present results may be explained on the assumption that there are two parallel transport paths, one above kink temperature takes place in the conduction band and another below kink temperature in the Y-rela-ted donor impurity band, Moreover, we estimated that the center of the impurity band lies about 0.06-0.07 eV below the conduction band E_C.