Si-Rich $\hbox {Si}_{\rm x}\hbox {C}_{1 - {\rm x}}$ Light-Emitting Diodes With Buried Si Quantum Dots

The nonstoichiometric ITO/n-SiC/i-SiC/p-Si/Al light-emitting diodes (LEDs) with dense Si quantum dots (Si-QDs) embedded in the Si-rich Si_xC_1-x -based i-SiC layer are demonstrated. The Si-rich Si_xC_1-x films with buried Si-QDs are grown by the plasma-enhanced chemical vapor deposition with varying substrate temperatures. After the annealing process, the average Si-QD size in the Si-rich Si_0.52C_0.48 film is 2.7 ± 0.4 nm with a corresponding volume density of 1.43 × 10¹⁸ cm^-3. By increasing the deposition temperatures from 300°C to 650°C, the turn-on voltage and turn-on current of the ITO/n-SiC/i-SiC/p-Si/Al LEDs are found to decrease from 13 to 4.2 V and from 0.63 to 0.34 mA, respectively. In addition, these Si-rich Si_xC_1-x LEDs provide the maximal electroluminescent (EL) power intensity increasing from 1.1 to 4.5 μW/cm². The yellow (at 570 nm) EL emission power of the ITO/n-SiC/i-SiC/p-Si/Al LEDs reveals a saturated phenomenon due to the Auger effect. The dissipated energy by the lattice thermal vibration contributes to a decayed EL emission power at higher biased currents. The corresponding power-current slope is observed to enhance from 0.45 to 0.61 μW/A with the substrate temperature increasing to 650°C.