ELECTROLUMINESCENCE OF EPITAXIAL GAP P-N STRUCTURES GROWN ON SI SUBSTRATES

The vapor-phase epitaxy method in an open chloride system was used to grow epitaxial gallium phosphide p-n structures on Si substrates. Elec trical and electroluminescence characteristics of the structures were investigated. At low values of the current (6 X 10(-8)-6 X 10(-4) A/cm 2) the current-voltage characteristic is of a tunnel nature. In the ca se of a forward current the I-V characteristic has an exponential shap e (with a preexponential factor of 10(-8) A/cm2 and a characteristic e nergy of 75 meV); in the case of a reverse current it obeys a power la w (with an exponent of 4). The current cutoff voltage is approximately 1.85 V, the breakdown voltage is 12-18 V and the differential resista nce is 4.5 OMEGA. The capacitance-voltage characteristic is quadratic, the cutoff voltage is 1.8 V, and the slope is -1.75 X 10(-4) pF-2 . V -1 . cm4. The p-n-GaP/n-Si structures emit visible light under a rever se bias. The wide electroluminescence spectrum decays at higher photon energies in the range 1.6-2.5 eV. The quantum efficiency of the elect roluminescence is 10(-3)% and it doesn't depend on the current. The ex perimental results are in agreement with the hypothesis of avalanche b reakdown (under a reverse bias in excess of 12-18 V), which occurs as a result of impact ionization that generates light.