226 nm AlGaN/AlN UV LEDs using p-type Si for hole injection and UV reflection

Abstract

Deep ultraviolet (UV) light-emitting diodes (LEDs) at a wavelength of 226 nm based on AlGaN/ AlN multiple quantum wells using p-type Si as both the hole supplier and the reflective layer are demonstrated. In addition to the description of the hole transport mechanism that allows hole injection from p-type Si into the wide bandgap device, the details of the LED structure which take advantage of the p-type Si layer as a reflective layer to enhance light extraction efficiency (LEE) are elaborated. Fabricated LEDs were characterized both electrically and optically. Owing to the efficient hole injection and enhanced LEE using the p-type Si nanomembranes (NMs), an optical output power of 225 lW was observed at 20 mA continuous current operation (equivalent current density of 15 A/cm 2) without external thermal management. The corresponding external quantum efficiency is 0.2%, higher than any UV LEDs with emission wavelength below 230 nm in the continuous current drive mode. The study demonstrates that adopting p-type Si NMs as both the hole injector and the reflective mirror can enable high-performance UV LEDs with emission wavelengths, output power levels, and efficiencies that were previously inaccessible using conventional p-in structures.

Low dimensional freestanding semiconductors for flexible optoelectronics: materials, synthesis, process, and applications

“…The abovementioned semiconductor NMs have been actively studied to enhance the performance of various electronic/optoelectronic devices such as reflectors [54], photodetectors [63][64][65], light-emitting diodes [66][67][68], and transistors [55,69]. They are either becoming the main body of the devices or adding additional functionalities as a key enabler for the enhanced performance.…”

Theoretical Prediction of Heterogeneous Integration of Dissimilar Semiconductor with Various Ultra-Thin Oxides and 2D Materials

“…Semiconductor heterojunctions have long been considered one of the most important building blocks of the semiconductor industry. They have led to various practical electronic and optoelectronic applications such as lighting devices (light-emitting devices and lasers), sensors, transistors, and photovoltaics [1][2][3][4][5][6][7]. All of these applications have used latticematched (or slightly mismatched) semiconductor systems such as Si/SiGe, GaAs/AlGaAs, or GaN/AlGaN [8][9][10].…”

Progress in External Quantum Efficiency for III‐Nitride Based Deep Ultraviolet Light‐Emitting Diodes

“…According to the research results by different groups, however, the external quantum efficiency (EQE) is still lower than 10% for DUV LEDs when the peak emission wavelength is shorter than 280 nm, and most of the reported efficiency droop is higher than 10% for the LEDs at deep ultraviolet range [see Figure (a,b)]. DUV LEDs with low EQE and significant efficiency droop effect cannot efficiently kill all the bacteria in the drinking water with high flow rate . As a result, before the massive penetration into the market to replace the conventional mercury based deep ultraviolet light source, it is essentially important to enhance the EQE for DUV LEDs.…”

“…Summary of the reported (a) EQE and (b) efficiency droop for DUV LEDs by different groups during the last 5 years (2014–2018) …”