A silicon-based InGaN/GaN microbelt blue light-emitting-diode fabricated via low-temperature direct bonding

Abstract

Integrating a nitride semiconductor light source on Si is a key to building wide-spectrum photonic systems; however, there have been many challenges in growing nitride semiconductors directly on a Si substrate. Herein, freestanding InGaN/GaN-based microbelts were first prepared by using the electrochemical lift-off (ELO) technique from an as-grown sapphire substrate. The obtained microbelts had uniform morphology and could be flexibly transferred. Subsequently, direct bonding technology was used to transfer and integrate the released InGaN/GaN-based microbelt onto a high conductivity Si substrate to fabricate an on-chip microbelt light-emitting diode (MBLED) with a vertical injection structure. An intermediate amorphous layer with a thickness of ∼25 nm was formed at the interface of GaN and Si, which was found to have no obvious negative effect on the electrical injection of the MBLED. The prepared Si-based InGaN/GaN MBLED emitted a 465 nm light at the end face of the microbelt with unidirectional luminescent waveguide properties. The luminescence intensity showed a high linear correlation with increasing current. Fowler–Nordheim tunneling (FNT) and thermionic emission (TE) were found to be responsible for its current transport mechanisms at low and high voltages, respectively. This study provides a simple, low-cost method for integrating III–V semiconductor devices on a Si substrate.