InGaN micro-light-emitting diodes monolithically grown on Si: achieving ultra-stable operation through polarization and strain engineering

Abstract

Micro or submicron scale light-emitting diodes (µLEDs) have been extensively studied recently as the next-generation display technology. It is desired that µLEDs exhibit high stability and efficiency, submicron pixel size, and potential monolithic integration with Si-based complementary metal-oxide-semiconductor (CMOS) electronics. Achieving such µLEDs, however, has remained a daunting challenge. The polar nature of III-nitrides causes severe wavelength/color instability with varying carrier concentrations in the active region. The etching-induced surface damages and poor material quality of high indium composition InGaN quantum wells (QWs) severely deteriorate the performance of µLEDs, particularly those emitting in the green/red wavelength. Here we report, for the first time, µLEDs grown directly on Si with submicron lateral dimensions. The µLEDs feature ultra-stable, bright green emission with negligible quantum-confined Stark effect (QCSE). Detailed elemental mapping and numerical calculations show that the QCSE is screened by introducing polarization doping in the active region, which consists of InGaN/AlGaN QWs surrounded by an AlGaN/GaN shell with a negative Al composition gradient along the c-axis. In comparison with conventional GaN barriers, AlGaN barriers are shown to effectively compensate for the tensile strain within the active region, which significantly reduces the strain distribution and results in enhanced indium incorporation without compromising the material quality. This study provides new insights and a viable path for the design, fabrication, and integration of high-performance µLEDs on Si for a broad range of applications in on-chip optical communication and emerging augmented reality/mixed reality devices, and so on.

60‐1: Invited Paper: Emerging microdisplay technologies for AR/VR applications

“…As indicated in Fig. 4(b), Wu et al designed and fabricated green InGaN/GaN nanowire LEDs on Si through a bottom-up selective area epitaxy process [28]. In this work, they also applied an AlGaN/GaN shell surrounding the MQW with a negative Al composition gradient along c-axis to suppress quantum-confined Stark effect (QCSE).…”

Characteristics of GaN-on-Si Green Micro-LED for Wide Color Gamut Display and High-Speed Visible Light Communication

“…When the current density rises from 0.1 to 1 kA/cm 2 , the EL peak wavelength of the GaN-on-Si green micro-LED shifts from 524.3 to 495.6 nm due to the quantum confinement Stark effect (QCSE) caused by the piezoelectric field in the MQWs. The severe wavelength blue shift is expected to be mitigated by special designs of quantum well structures or the introduction of the optical microcavity. ,, At the same time, the FWHM of the micro-LED will also increase from 20.2 to 44 nm, when the operating current density increases from 0.1 to 1 kA/cm 2 . It has been reported that green LEDs with EL peak wavelengths in the range of 525–535 nm and FWHM not exceeding 25 nm can meet the requirements of the Rec.…”

“…When The severe wavelength blue shift is expected to be mitigated by special designs of quantum well structures or the introduction of the optical microcavity. 8,23,24 At the same time, the FWHM of the micro-LED will also increase from 20.2 to 44 nm, when the operating current density increases from 0.1 to 1 kA/cm 2 . It has been reported that green LEDs with EL peak wavelengths in the range of 525−535 nm and FWHM not exceeding 25 nm can meet the requirements of the Rec.…”

Exciton–polariton light-emitting diode based on a single ZnO superlattice microwire heterojunction with performance enhanced by Rh nanostructures

“…14–21 Therefore, 1D superlattice micro/nanostructures can function as ideal building blocks for developing easily manufactured, miniaturized and integrated electronics and photonic devices. 22–26…”

“…[14][15][16][17][18][19][20][21] Therefore, 1D superlattice micro/nanostructures can function as ideal building blocks for developing easily manufactured, miniaturized and integrated electronics and photonic devices. [22][23][24][25][26] For the past few years, several cleverly-designed thermal evaporation schemes have been proposed to prepare 1D semiconductor superlattice micro/nanowires, with segmented structures that could be modulated along the axial direction longitudinally. 9,11,27 This type of periodic composition of 1D superlattice crystals has aroused wide public interest due to the intriguing electronic and optical transport properties.…”