Contact Resistivity and Barrier Height of Al/Ti Ohmic Contacts on p-Type Ion Implanted 4H- and 6H-SiC
Contact Resistivity and Barrier Height of Al/Ti Ohmic Contacts on p-Type Ion Implanted 4H- and 6H-SiC
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DOI：
10.4028/www.scientific.net/msf.457-460.881
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发表时间：
2004-06
期刊：
影响因子：
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通讯作者：
A. Scorzoni;F. Moscatelli;A. Poggi;G. Cardinali;R. Nipoti
中科院分区：
文献类型：
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作者：
A. Scorzoni;F. Moscatelli;A. Poggi;G. Cardinali;R. Nipoti
最近发现，Al含量为70wt%的Al-Ti合金在1000℃真空退火2分钟后，在外延和注入p型碳化硅上的接触电阻率ρ_c重复性最好。本文分析了这种Al-Ti合金的接触电阻率，旨在提取肖特基势垒高度，特别是p型离子注入的4H和6H-碳化硅样品。对于中/高掺杂浓度，即4×10 19 cm-3，用传输线法测得的ρc值始终小于2×10-4Ωcm2。此外，还发现有相当一部分值低于1×10-6Ωcm2的最小分辨率。根据热离子场发射模型，从接触电阻率中提取了势垒高度φB作为温度的函数，对于所有具有大于最小分辨率的ρc的芯片。对于这些芯片，6H-SiC外延层的φB为(0.5 3±0.0 5)eV，注入4H-SiC为(0.82±0.0 8)eV，注入6H-SiC为(0.95±0.0 8)eV。研究发现，ρc小于最小分辨率的晶片，其势垒高度可能与外延层的势垒高度相似。
Recently, the Al-Ti alloy with the 70 wt% Al was found to give the most reproducible contact resistivity ρc on epitaxial and implanted p-type SiC after vacuum annealing at 1000°C for 2 min. In this work contact resistivity values of this Al-Ti alloy are analyzed aiming at extracting the Schottky barrier height with particular attention to p-type ion implanted 4Hand 6H-SiC specimens. The ρc values extracted from Transmission Line Method measurements were always lower than 2×10 -4 Ωcm 2 for a medium/high doping concentration of the implanted layers, i.e. 4×10 19 cm -3 . Moreover, a significant portion of values below the minimum resolution of 1×10 -6 Ωcm 2 was found. The barrier height φB has been extracted from the contact resistivity as a function of the temperature, according to the thermionic-field emission model, for all the dies featuring a ρc greater than the minimum resolution. For these dies the φB is (0.53±0.05) eV for the 6H-SiC epilayer, (0.82±0.08) eV for the implanted 4H-SiC and (0.95±0.08) eV for the implanted 6H-SiC. It was found that the dies which have a ρc minor than the minimum resolution could feature a barrier height similar to that found on the epilayer.