Formation of diamond p-n junction and its optical emission characteristics

摘要

We have succeeded in forming diamond p-n junction diodes and confirmed their ultraviolet (UV) light emission during forward-current operation. The p-n junctions was formed from a boron doped p-type diamond layer and phsophorus doped n-type diamond layer grown epitaxially on the {111} surface of single crystalline diamond. The p-n junction exhibited good diode characteristics. The rectification ratio was over five orders in magnitude at +-10 V. Turn-on voltage has been observed at approximately 5 V which is close to the expected built-in potential. Over forward bias of approximately 20 V, storng UV light emission at 235 nm was observed, with broad band emission near 4.5 eV and A-band in a visible region appeared simultaneously. The 235-nm light emission is attributed to free exciton recombination coupled with transverse-optical phonon.