Narrow-Linewidth GaN-on-Si Laser Diode with Slot Gratings

Area of Science:

• Semiconductor device physics
• Optoelectronics
• Materials science

Background:

• Gallium Nitride-on-Silicon (GaN-on-Si) laser diodes are crucial for optoelectronic applications.
• Conventional distributed Bragg feedback (DBF) laser diodes often suffer from performance degradation due to complex grating fabrication.
• Narrow linewidths are essential for high-performance laser applications.

Purpose of the Study:

• To demonstrate room-temperature, electrically pumped, narrow-linewidth GaN-on-Si laser diodes.
• To mitigate the negative impacts of grating fabrication on device performance.
• To improve the efficiency and reduce leakage currents in GaN-on-Si lasers.

Main Methods:

• Incorporation of a few precisely defined slot gratings into conventional Fabry-Pérot cavity laser diodes.
• Utilized a subsequent wet etching process using tetramethyl ammonium hydroxide (TMAH) solution.
• TMAH etching effectively repaired dry etching-induced damages and smoothed slot sidewalls.

Main Results:

• Successfully demonstrated room-temperature, electrically pumped narrow-linewidth GaN-on-Si laser diodes.
• Achieved a reduction in threshold current by over 20%.
• Decreased reverse leakage current by over three orders of magnitude.

Conclusions:

• The novel slot grating approach significantly enhances GaN-on-Si laser diode performance.
• The optimized fabrication process, including TMAH wet etching, is key to device success.
• This work paves the way for more efficient and reliable GaN-on-Si laser diodes.