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Stimulated emission at 288 nm from silicon-doped AlGaN-based multiple-quantum-well laser
Optics Express
|May 14, 2015
Summary
Silicon doping in aluminum gallium nitride (AlGaN) multiple-quantum-well (MQW) lasers significantly lowers the threshold for ultraviolet (UV) light emission. This enhancement is attributed to improved crystal quality and higher internal quantum efficiency (IQE) in doped AlGaN MQWs.
Area of Science:
- Materials Science
- Optoelectronics
- Semiconductor Physics
Background:
- Ultraviolet (UV) lasers are crucial for various applications, including sterilization, sensing, and lithography.
- Achieving efficient UV laser emission, particularly in the deep UV spectrum, remains a significant challenge due to material limitations and efficiency issues.
- Aluminum Gallium Nitride (AlGaN) based multiple-quantum-wells (MQWs) are promising candidates for UV optoelectronic devices.
Purpose of the Study:
- To investigate the effect of silicon doping on the performance of AlGaN-based MQW UV lasers.
- To understand the underlying mechanisms responsible for improved lasing characteristics in silicon-doped AlGaN MQWs.
- To demonstrate stimulated emission at 288 nm using silicon-doped AlGaN MQWs.
Main Methods:
- Fabrication of silicon-doped and undoped AlGaN-based MQW structures on sapphire substrates.
- Optical pumping experiments to determine the lasing threshold energy density.
- Measurement of internal quantum efficiency (IQE) for both doped and undoped samples.
- Transmission electron microscopy (TEM) for crystallographic quality assessment.
- Theoretical calculations of polarization charge and internal polarization fields.
Main Results:
- Stimulated emission was achieved at 288 nm in silicon-doped AlGaN MQW UV lasers.
- The optical pumping threshold energy density was measured to be 64 mJ/cm2 for doped samples.
- No lasing behavior was observed in undoped AlGaN MQWs under similar conditions.
- Silicon-doped AlGaN MQWs exhibited a 41% higher internal quantum efficiency (IQE) compared to undoped ones.
- TEM analysis revealed improved crystallographic quality in silicon-doped MQWs.
Conclusions:
- Silicon doping is an effective strategy to reduce the lasing threshold and enhance the performance of AlGaN-based UV lasers.
- The improved performance is primarily due to enhanced crystallographic quality and increased internal quantum efficiency (IQE) resulting from silicon doping.
- The benefits of improved structural quality in silicon-doped AlGaN MQWs outweigh the reduction in the internal polarization field, leading to successful stimulated emission.
