LARGE-AREA FIELD EMISSION DIODE FOR SEMICONDUCTOR ANNEALING.

The characteristics of a low energy electron beam generator used for annealing of materials of interest as electron devices and photovoltaic cells are reported. The high voltage pulser is a two-stage Marx circuit which supplies 10-50 kV pulses. A Blumlein line gives the pulses an almost square shape and a length of 50 ns. This short pulse is applied to a field emission diode. Various kinds of cathodes are used. They deliver electron pulses of up to 20 kA. Tungsten needles are used for small-area beams and blade arrays or graphite cathodes for large-area beams. Consequently, the beam diameter can vary from 2 to 120 mm with a good beam homogeneity. The anode is movable to vary the vacuum diode impedance and consequently the current-voltage characteristic of the electron beam. Energy densities varying from 0. 1 to 100 J/cm**2 are obtained on the anode. The anode can be formed by a semiconductor monocrystalline wafer. Authors used crystalline silicon wafers covered by a thin ( approximately equals 100 nm) layer of vacuum deposited near-noble and refractory metals. Under electron beam bombardment with discharge energy densities ranging from 0. 4 to 10 J/cm**2, silicide formation is evident over all the annealed anodes. Metastable compounds are formed because of the fast heating and cooling rates. Silicon monocrystalline wafers, doped with 10**1**4-10**1 5 ions/cm**2 of B or P ions exhibit a complete recovery of their crystalline structure after a single discharge.