Tailoring in-Plane Permittivity Gradients by Shadow Mask Molecular Beam Epitaxy.

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Infrared (IR) gradient permittivity materials are crucial for developing miniature IR devices like on-chip spectrometers.
• Manufacturing these materials with horizontal permittivity variations is challenging.
• High crystalline quality and tunable properties are essential for practical applications.

Purpose of the Study:

• To demonstrate the control of permittivity gradient length and steepness in Si:InAs films.
• To investigate the effect of shadow mask thickness on gradient properties.
• To establish a method for creating tunable in-plane permittivity gradients.

Main Methods:

• Utilized shadow mask molecular beam epitaxy (MBE) for Si:InAs film growth.
• Varied shadow mask thickness (200 µm and 500 µm) to influence material properties.
• Analyzed permittivity gradient width and steepness on flat and sloped surfaces.

Main Results:

• Demonstrated control over permittivity gradient width (18-39 µm) and steepness (9.1-23.3 cm⁻¹/µm) by adjusting shadow mask thickness.
• Observed distinct gradient characteristics on flat mesas versus film slopes.
• Confirmed tunability of in-plane permittivity gradients in Si:InAs films.

Conclusions:

• Successfully controlled in-plane permittivity gradients in Si:InAs films via shadow mask MBE.
• The findings pave the way for fabricating advanced, miniaturized IR devices.
• This method offers a pathway to engineer material properties for specific optoelectronic applications.