Takashi Hatai

Key role of nanocrystalline feature in porous polycrystalline silicon diodes for efficient ballistic electron emission

The cold electron emission characteristics of nanocrystalline porous polysilicon (PPS) diodes have been investigated for two PPS diodes prepared under different conditions. The origin of the difference in the emission efficiency and electron energy distribution between the two samples is analyzed in relation to the respective photoluminescence properties. The photoluminescence spectrum in the efficient electron emitter consists of red and blue emission bands corresponding to nanocrystalline silicon and interfacial oxide, respectively, while that in the low-efficiency emitter consists only of a blue band. Too much oxidation results in a reduction of the emission efficiency due to increased electron scattering. It is evident that both the formation of nanocrystalline silicon and its appropriate surface oxidation are key issues for obtaining efficient ballistic emission. These results are consistent with the emission model that electrons are accelerated in the PPS layer by multiple tunneling through interfac...

Fabrication of a 7.6-in.-diagonal prototype ballistic electron surface-emitting display on a glass substrate

A prototype ballistic electron surface-emitting display (BSD) was fabricated on a TFT or PDP glass substrate by using a low-temperature process. A 84 x 63-pixel, 7.6-in.-diagonal full-color BSD shows excellent performance, comparable to the previously reported 2.6-in. model. This result demonstrates the strong possibility of large-panel BSDs.

Direct excitation of xenon by ballistic electrons emitted from nanocrystalline-silicon planar cathode and vacuum-ultraviolet light emission

— To verify the possible use of energetic electrons for direct excitation of inert gas molecules, a nanocrystalline-silicon (nc-Si) planar ballistic emitter is operated in a high-pressure xenon gas ambience. Under the pulse drive, vacuum-ultraviolet (VUV) light emission is detected without any signs of discharge. The transient behavior of the VUV light emission properly corresponds to that of the nc-Si emitter. In accordance with quantitative analyses of electron-emission characteristics and the VUV output, the electron-to-photon conversion efficiency reaches 81% in the relatively efficient emitter case. The VUV output power is mainly determined from the number of electrons with energies compatible the with internal excitation of xenon. The emission spectrum observed at a pressure of 10 kPa shows peaks at 152 and 172 nm, which are thought to be originated from metastable Xe2* states. In contrast to the case of conventional impact ionization, no near-infrared (NIR) peaks are seen in the spectrum. These results strongly suggest that the incidence of energetic electrons causes direct excitation of xenon molecules followed by radiative relaxation through intermediate states. The generated VUV light can be easily converted to visible light using a phosphor screen. As a discharge-free VUV light emission, this phenomenon is potentially applicable to mercury-free, high-efficacy, and high-stability flat-panel light-emitting device.

39.3: Development of a Low Temperature Process of Ballistic Electron Surface-Emitting Display (BSD) on a Glass Substrate

Ballistic electron Surface-emitting Display (BSD) is successfully fabricated on a glass substrate with low temperature process. 168 (RGB) × 126 pixels, 2.6 inches diagonal full-colour BSD exhibits excellent performance as a flat panel display. Main fabrication process is an anodisation and subsequent electrochemical oxidation process at a low temperature, which will contribute to larger panel size and process-cost reduction.

Vacuum-ultraviolet light emission from xenon directly excited by ballistic output electrons of nanocrystalline silicon planar cathode

The effect of electron incidence into xenon gas molecules has been investigated by using a nanocrystalline silicon (nc-Si) planar ballistic emitter. Vacuum-ultraviolet light emission is observed without discharging when the nc-Si device is driven in xenon gas. The emission spectrum of xenon at 10kPa shows peaks at 152 and 172nm which originate from Xe2* radiation. These results strongly suggest that energetic electrons directly excite xenon molecules followed by radiative relaxations. The observed effect is potentially applicable to mercury-free, efficient, and stable flat panel light sources.

14.1: Invited Paper: Fabrication of Ballistic Electron Surface-Emitting Display on Glass Substrate

It is demonstrated that the Ballistic electron Surface-emitting Display (BSD) can be fabricated onto both quartz and TFT Glass substrates and performed excellent characteristics. We also demonstrate the 2.6 inches diagonal 84(RGB)×63 pixels multicolour flat panel display on a quartz glass substrate. BSD promise the possible application to the flat panel display in near future.

28.4: Matrix Flat-Panel Application of Ballistic Electron Surface-Emitting Display

Ballistic electron Surface-emitting cold cathode based on porous polysilicon exhibits excellent performance as a novel flat panel display. It is demonstrated that emission current is stable up to an ambient pressure of 10 Pa. 53(RGB) × 40 pixels multicolour matrix panel is fabricated and evaluated its performance. Fabricating process is mainly based on conventional silicon process and anodisation process, for which we can expect lower production cost at larger panel fabrication.