III-Nitride Light-Emitting Devices

Abstract

III-nitride light-emitting devices have been subjects of intense research for the last several decades owing to the versatility of their applications for fundamental research, as well as their widespread commercial utilization. Nitride light-emitters in the form of light-emitting diodes (LEDs) and lasers have made remarkable progress in recent years, especially in the form of blue LEDs and lasers. However, to further extend the scope of these devices, both below and above the blue emission region of the electromagnetic spectrum, and also to expand their range of practical applications, a number of issues and challenges related to the growth of materials, device design, and fabrication need to be overcome. This review provides a detailed overview of nitride-based LEDs and lasers, starting from their early days of development to the present state-of-the-art light-emitting devices. Besides delineating the scientific and engineering milestones achieved in the path towards the development of the highly matured blue LEDs and lasers, this review provides a sketch of the prevailing challenges associated with the development of long-wavelength, as well as ultraviolet nitride LEDs and lasers. In addition to these, recent progress and future challenges related to the development of next-generation nitride emitters, which include exciton-polariton lasers, spin-LEDs and lasers, and nanostructured emitters based on nanowires and quantum dots, have also been elucidated in this review. The review concludes by touching on the more recent topic of hexagonal boron nitride-based light-emitting devices, which have already shown significant promise as deep ultraviolet and single-photon emitters.

Deep‐Ultraviolet Micro‐LEDs Exhibiting High Output Power and High Modulation Bandwidth Simultaneously

“…Group III nitride materials and devices have experienced rapid development over the past two decades. [ 1 ] In virtue of its direct and wide bandgap, high‐efficiency light‐emitting diodes (LEDs) ranging from the infrared to ultraviolet bands have been realized. [ 1a ] Since the first report on ultraviolet (UV) LEDs with an emission wavelength shorter than 360 nm in 1998, [ 1b ] a new era of AlGaN‐based deep‐UV (DUV) LEDs has been started.…”

“…Creating a solar‐blind communication (SBC), which operates at a wavelength between 200 and 280 nm, has attracted significant interest. Compared to conventional visible‐light communication, using DUV wavelength (200–280 nm) light as a signal carrier for SBC has unique features such as background noise negligibility, [ 1c ] non‐line‐of‐sight communication, and so on. [ 2 ] It provides high security for military‐tactical communication systems.…”

“…For SBC application, AlGaN‐based DUV micro‐LEDs (µ‐LEDs), [ 5e,5f ] with the emission region (mesa) dimension down to sub‐100 µm range, are the best candidate for their improved modulation bandwidth in virtue of the small resistance–capacitance (RC) time constant, [ 7 ] high current densities, and short carrier lifetime. [ 1c ] At present time, DUV µ‐LEDs, working around 270 nm, have achieved a 400 MHz modulation bandwidth. [ 1c ] However, its light output power (LOP) is relatively small with a value of <1 mW and wall‐plug efficiency (WPE) is smaller than 1%.…”

“…[ 1c ] At present time, DUV µ‐LEDs, working around 270 nm, have achieved a 400 MHz modulation bandwidth. [ 1c ] However, its light output power (LOP) is relatively small with a value of <1 mW and wall‐plug efficiency (WPE) is smaller than 1%. These values are too low to satisfy the requirement of a long transmission distance.…”

Review of Low-Frequency Noise Properties of High-Power White LEDs during Long-Term Aging

“…Top-quality light sources are of high interest in industrial, science, medicine, military, and daily life applications. Light-emitting diodes (LEDs) are smaller, cheaper, operate at lower power, and have longer lifetime than other light sources (lamps or lasers) [ 1 , 2 ]. The simplicity and high reliability of LEDs make them an attractive choice for short-distance, moderate-speed optical data links, or for visible light communication systems [ 3 , 4 , 5 , 6 ].…”