Investigation of deep-level defects in conductive polymer on n-type 4H- and 6H-silicon carbide substrates using Ⅰ-ⅤI and deep level transient spectroscopy techniques

摘要

The current-voltage (Ⅰ-Ⅴ) characteristics of Au/sulfonated polyaniline (SPAN)-SiC heteroj unctions have been investigated in detail over a w;de range of temperatures between 20 and 440 K. The measured I-V characteristics of all devices show a good rectification behavior at all temperatures. The room temperature rectification ratios (forward to reverse currents ratio, I_f/I_r) at 0.6 V for SPAN-type 4H-SiC and SPAN-type 6H-SiC heterojunctions are 2 x 104 and 7 x 106, respectively. The value of rectification of SPAN/6H-SiC heterojunction is four orders of magnitutude higher than the state-of-the art sulfonated polyaniline thin films deposited on n-type silicon substrates. A self-assembly technique and copolymerization were used to fabricate a self-doped polyaniline films on SiC substrates. The experimental Ⅰ-Ⅴ　 data were analysed using the Werner model, which includes the series resistance of the heterojunctions. The diode parameters such as the ideality factor and the barrier height are determined from the experimental data using I-V analysis method. The effect of the temperature on these parameters is presented. Deep level transient spectroscopy (DLTS) and Laplace DLTS techniques were used to investigate the electrically active defects present in these heterostructure devices.