The electrical characteristic of Si NC LED with the SLs was improved. Moreover, light emission efficiency and wall-plug efficiency (WPE) of the Si NC LED with the SLs were also enhanced by 50% and 40%, respectively. Methods The Si NCs used here were embedded into a SiN x matrix with a thickness of 50 nm and were in situ grown by PECVD, in which Ar-diluted 10% SiH4 and NH3 was used as the source of reactants.

The plasma power, chamber pressure, and substrate temperature for the growth of Si NCs were fixed at 5 W, 500 mTorr, and 250°C, respectively. The size of Si NCs Selleck STI571 embedded into a SiN x was around 4 nm, which was confirmed by high-resolution transmission electron microscopy (HRTEM) [10]. No post annealing process was performed to create the Si NCs into the SiN x matrix after the growth. SiCN (3 nm)/SiC (3 nm) SLs at 5.5 periods doped with phosphorous (P) was deposited on the Si NCs which were embedded into the SiN x matrix at 300°C by a PECVD. The SiCN/SiC SLs were grown by changing the

flow rates of CH4 and NH3 sources while the flow rate of SiH4 was fixed. An amorphous SiC film (approximately 40 nm) doped with P that is used as an electron injection layer was deposited on the 5.5 periods of SiCN/SiC SLs. An ITO layer (100 nm) used as a transparent current spreading layer was deposited at 150°C on an amorphous SiC film and then annealed at 300°C for 30 min in a selleck kinase inhibitor pulsed laser deposition chamber to improve the electrical property and optical transparency. Entospletinib order Right after the deposition of ITO, the Si NC LED samples were etched using an inductively coupled SF6/O2 plasma and standard photolithographic technique until the Si layer was exposed. Finally, a Ni/Au (30/120 nm) layer was deposited for the top and backside contacts Baricitinib using thermal evaporation. A mesa-type Si NC LED with 5.5 periods of SiCN/SiC SLs with an area of 300 × 300 μm2 was fabricated, and

Si NC LED without SiCN/SiC SLs was also fabricated for comparison. Results and discussion Figure  1a shows a schematic illustration of the Si NC LED with 5.5 periods of SiCN/SiC SLs. The SiCN/SiC SLs were designed by considering the optical bandgap to increase the electron injection into the Si NCs due to the formation of 2-DEG at the interface between the SiCN layer and SiC layer. Since SiN has a higher bandgap than SiC, the optical bandgap of the SiCN layer can be tuned by changing the N composition. By increasing the N composition in the SiCN layer, the optical bandgap would be increased. A higher optical bandgap has an advantage for enhancing the light extraction efficiency of Si NC LED since the photons generated in the Si NC layer can easily escape outside the LED by decreasing the absorption of photons at the SLs. In the previous result [16], however, we found that the SiCN layer showed an insulating property when the N composition in the SiCN layer exceeded over 20%.