Basic studies of the vacuum ICs

tunnelling emitter is expected to have very promising characteristics as a cathode of vacuumtubes;because its higher emission density, lower noise temperature, higher reliability and so oncompared with those of usual thermal cathode.我们已尝试开发tunnelling emitter arrayswith the -insulator-semiconductor structure (MIS). In this structure，it is expected to be able to deposit a high quality insulator film on semiconductor by usingsemi-conductor processing technologies and to apply uniform electric field on MIS diode. We formedultrathin al_2_3 and sio_2 films on-n-Si wafer (100). We showed that the single crystal gamma andalpha- al_2_3 films were grown on n-si substrate at the substrate temperature of 650 - C和750 - C，respectively,by the molecular layer epitaxy method. sio_2 films were formed by the chemical oxidation and theplasmasputtering methods. The properties of film former method investigated to begood for the tunnelling emitter use comparing with the latter.The arrays with MIS structurewere constructed by evaporating thin metal films on the insulator layers and the I-Vcharacteristics were measured and compared with the theoretical studies of MIS tunnel diode.Up tothe present,it can be stated that good quality ultrathin insulator layers can be formed on n-Si by the chemicaloxidation method and the dominant charge transport mechanism through the oxide layer is tunnellingin the MIS diode structure。

The tunnelling emitter is expected to have very promising characteristics as a cathode of vacuum tubes; because its higher emission density, lower noise temperature, higher reliability and so on, compared with those of usual thermal cathode. We have tried to develop the tunnelling emitter arrays with metal-insulator-semiconductor structure (MIS). In this structure, it is expected to be able to deposit a high quality insulator film on semiconductor by using semi-conductor processing technologies and to apply uniform electric field on MIS diode. We formed ultrathin Al_2O_3 and SiO_2 films on-n-Si wafer (100). We showed that the single crystal gamma and alpha-Al_2O_3 films were grown on n-si substrate at the substrate temperature of 650゜C and 750゜C, respectively, by the molecular layer epitaxy method. SiO_2 films were formed by the chemical oxidation and the plasmasputtering methods. The properties of film formed by the former method were investigated to be good for the tunnelling emitter use comparing with that by the latter.The arrays with MIS structure were constructed by evaporating thin metal films on the insulator layers and the I-V characteristics were measured and compared with the theoretical studies of MIS tunnel diode.Up to the present, it can be stated that good quality ultrathin insulator layers can be formed on n-Si by the chemical oxidation method and the dominant charge transport mechanism through the oxide layer is tunnelling in the MIS diode structure.