Electrical and optical properties of light-emitting p–i–n diodes on diamond

Electrical and optical properties of light-emitting p–i–n diodes made on natural and synthetic single-crystal diamonds were studied at temperatures up to 500 °C. The diodes were fabricated by boron (p-type doping) and lithium or phosphorous (n-type doping) ion implantation in the form of two adjacent p- and n-type areas separated by an undoped i gap of a width varying from 2 to 200 μm. The current–voltage characteristics of the diodes showed typical rectifying behavior. Onset of the forward current is accompanied by electroluminescence (EL) and occurred at a certain voltage depending on the width of the i base and the type of the diamond substrate. At the onset voltage a current-controlled negative resistance regime was observed. Comparison of the electrical characteristics of the diodes with the optical properties of the corresponding diamond substrates revealed that in diamonds with nitrogen content over 5×1017 cm−3 the nitrogen defects are the major recombination centers affecting the carrier lifetime. EL of the A band, the nickel related 484 nm center, and the nitrogen related H3 and 575 nm centers, were excited in the diodes. The H3 and 575 nm centers retained considerable emitting intensity at temperatures as high as 500 °C. EL of the 484 nm center was possible to observe up to a temperature of 400 °C. EL of the A band was quenched rapidly with temperature and it disappears at above 200 °C.