| The concern about heterojunction is more and more prevalent since the big progress on Bandgap Engineering. Different band gaps between two kinds of semiconductor,the interface states, and so on, all that the factors provide a new characteristic for heterojunctions comparing with the homojunctions. Research on nano-crystalline films (such as: ZnO, SiC etc.) lead us a new way to fabricate heterojunctions. As the development of CVD (chemical vapor deposition) technology, nano-films are available through LPCVD (low pressure chemical vapor deposition) and PECVD (plasma enhancement chemical vapor deposition).A Nano-crystalline silicon film which was deposited by LPCVD in this paper was joined with crystal silicon by CMOS planar process as a nano-crystalline silicon/crystal silicon homo-type heterojunction diode. We detect this nano-film by SEM (scanning electron microscope). The I-V,C-V,temperature characteristics were measured and discussed. The result shows that the nano-crystalline silicon/crystal silicon heterojunction diode has a rectifying characteristic when it connected with substrate as a pn-junction. The leakage current under reverse bias is between 10-10 and 10-12A.The turn-on voltage is about 0.37V (room temperature). The I-V characteristics are hardly variated with the temperature. Turn-on voltage only reduces 0.025V when the temperature increases 10℃.The fabrication of the nano-crystalline silicon/crystal silicon heterojunction diode is simple, which can be achieved by CMOS planar process. It can also intergrade with other semiconductor components(such as collector of heterojunction transistor,pressure sensor, etc.). LPCVD was widely used by semiconductor foundry. The heterojunction has a very promising future since its well performance on so many characteristics. |
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