Optical control of internal electric fields in band gap-graded InGaN nanowires

Area of Science:

• Semiconductor Nanowires
• Optoelectronics
• Materials Science

Background:

• Indium gallium nitride (InGaN) nanowires are promising for optoelectronic applications.
• Controlled indium grading in nanowires is key to novel device functionalities.

Purpose of the Study:

• To investigate the effect of linearly graded indium content in InGaN nanowires.
• To explore the photocurrent generation and response dynamics in these graded nanowires.
• To demonstrate a new type of nanowire-based photodetector.

Main Methods:

• Fabrication of InGaN nanowires with linearly graded indium composition.
• Measurement of photocurrent as a function of photon flux.
• Quantitative band structure simulations.
• Ultrafast photocurrent response time measurements.

Main Results:

• Linear grading of indium content induces an internal electric field.
• A sign change in photocurrent was observed with varying photon flux, indicating negative differential photocurrent.
• Photocurrent response time was measured to be as fast as 1.5 picoseconds.

Conclusions:

• Graded InGaN nanowires can generate photocurrent due to induced internal electric fields.
• The observed negative differential photocurrent behavior opens possibilities for advanced photodetector designs.
• The ultrafast response time highlights the potential of these nanowires in high-speed optoelectronic devices.