Blue-Green Light Emission From Si and SiC Quantum Dots Co-Doped Si-Rich SiC $p\hbox {-}i\hbox {-}n$ Junction Diode

Si quantum dots and SiC quantum dots (SiC-QDs) codoped Si-rich silicon carbide (Si_xC_1-x) based p-i-n junction lightemitting diodes (LEDs) with blue light emission is demonstrated. By growing the Si_xC_1-x with plasma-enhanced chemical vapor deposition at relatively low temperature, the turn-on voltage of Si-rich Si_xC_1-x LEDs can be reduced to 6.1 V when thinning i-Si_xC_1-x layer to 25 nm because of higher tunneling probability and lower series resistance. The electroluminescent (EL) power increases to 136 nW, however, which inversely attenuates due to the reduced SiC-QDs if the i-Si_xC_1-x thickness further shrinks to 25 nm. The principle EL peak at 500 nm with narrower shape and blue-green emission pattern is attributed to the self-trapped excitons at surface states among SiC-QDs. The external quantum efficiency (EQE) of the Si-rich Si_xC_1-x LEDs with i-Si_xC_1-x thickness of 50 nm is up to 1.58 × 10^-1% with enhanced carrier tunneling probability. The carrier injection efficiency is enhanced to 46% by increasing the doping concentration to 10¹⁶ cm^-3, leading to almost one order of magnitude improvement on the EQE of Si-rich Si_xC_1-x LEDs.