Direct Optical Lithography Enabled Multispectral Colloidal Quantum-Dot Imagers from Ultraviolet to Short-Wave...

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Physics

Background:

• Complementary metal oxide semiconductor (CMOS) sensors are vital in optoelectronics but limited to visible and near-infrared spectra.
• Expanding sensing capabilities to ultraviolet (UV) and short-wave infrared (SWIR) is crucial for applications like fingerprint identification and night vision.

Purpose of the Study:

• To demonstrate multispectral broad-band CMOS-compatible imagers capable of capturing UV, visible, and SWIR light.
• To integrate UV-enhanced visible and SWIR pixels onto a single CMOS imager using colloidal quantum dots (CQDs).

Main Methods:

• Layer-by-layer direct optical lithography of colloidal quantum dots (CQDs) was employed.
• CQDs were integrated to create UV-enhanced visible pixels and SWIR pixels on a CMOS platform.

Main Results:

• High-resolution single-color and merged multispectral images were successfully obtained from a single imager.
• The developed imagers exhibited low photoresponse nonuniformity (PRNU) below 5% and a 0% dead pixel rate.
• Room-temperature responsivities reached 0.25 A/W at 300 nm (UV), 0.4 A/W at 750 nm (visible), and 0.25 A/W at 2.0 μm (SWIR).

Conclusions:

• The successful implementation of CQD-based multispectral imagers significantly broadens the spectral range of CMOS sensors.
• This technology enables advanced imaging capabilities for diverse applications requiring UV, visible, and SWIR detection in a single device.