Low-voltage high-efficiency light emitting diodes with lateral-current injection based on truncated Si/SiO_2 quantum wells

摘要

An efficient low-voltage lateral current-injection CMOS-compatible light emitting diode (LED) based on Si/SiO_2 multiple quantum wells (MQW) is reported. This is the first time that a lateral current-injection LED is demonstrated with Si/SiO_2 MQW structures. Strong electroluminescence (EL) in the wavelength ranging from 450 to 850 nm can be observed when the device is reverse-biased at the voltage of as low as ～6 V with the current of ～1 mA. With the lateral current injection structure, the working voltage of the LED is significantly reduced because the voltage is fully applied across the active region instead of dielectrics which cannot be avoided in vertical current-injection Si/SiO_2 quantum well LEDs that have received intensive research attention during the last decade. The external quantum efficiency is ～20 times higher than that of the conventional vertical current-injection LEDs based on Si/SiO_2 MQW. The light emission would probably originate from the impact ionization due to the hot carriers generated in ultra-thin Si film when the device is reverse-biased. The lateral configuration provides a versatile technology platform, since many light-extraction and mono-chromaticity enhancement techniques can be directly applied onto the top emission window.