Design and characterization of a pyroelectric detector based on three-dimensional structured hafnium oxide thin films

Abstract

Pyroelectric detectors are used for gas analysis and flame detection because of their fast response and excellent performance. Most pyroelectric devices are based on monocrystalline lithium tantalate or pyroelectric lead zirconate titanate thin films deposited on a silicon (Si) substrate. In comparison, recently discovered pyroelectric-doped hafnium oxide (HfO 2 ) offers the possibility of manufacturing completely complementary metal-oxide-semiconductor (CMOS)compatible devices on large Si wafers. This is a promising approach to simplifying mass production of the sensor element and realizing new sensor structures with a high performance. Si substrates were structured with trenches and filled with thin-doped HfO 2 layers by atomic layer deposition to multiply the pyroelectric current responsivity. An effective pyroelectric coefficient of up to 1300 μC∕m 2 ∕K was measured. Micromechanical structuring of the 6-in Si wafers was used to improve the thermal conversion of the sensor element. The applied plasmonic absorbers increase the infrared light absorption to >80% for the spectral range of 3 to 5 μm, which was determined using Fourier transform infrared reflection measurements. In the first step, the performance of the sensor element was evaluated with an analog transimpedance amplifier with a feedback resistance of 5 GΩ. A specific detectivity D Ã > 1 • 10 7 cm p Hz∕W was measured for the frequency range of 1 to 10 Hz. In addition, an application-specific integrated circuit was designed for the electrical signal conditioning to build a fully CMOScompatible pyroelectric detector. It offers a simple to manufacture, flexible configuration, and digital communication interface with a signal-to-noise performance close to analog detectors. We present the measurement results of different sensor elements and detector types.

CMOS AlN and ScAlN Pyroelectric Detectors with Optical Enhancement for Detection of CO2 and CH4 Gases

“…wafer. With CMOS‐compatible pyroelectric detectors gaining traction in recent years, [ 33,65 ] the adoption of CMOS‐compatible pyroelectric thin films for gas sensing not only allow for wafer‐level manufacturing, scalability toward 8‐ and 12‐in. production, but also integrable with CMOS electronics.…”

“…wafers using low thermal budget or reduced high temperature processing steps help with cost and energy savings in device fabrication. CMOS pyroelectric materials [33] include hafnium oxide (HfO 2 )-based, [34,35] gallium nitride (GaN)based, [36,37] aluminum nitride (AlN)-based, [38][39][40] and zinc oxide (ZnO)-based. [41] Among these materials, AlN and its doped counterpart scandium aluminum nitride (ScAlN) are attractive due to its high Curie temperatures above 1000 °C [38,42] and have not only piezoelectric, pyroelectric, and ferroelectric properties, [43,44] but also suitable for photonics from UV to mid-IR wavelengths [45,46] and power electronics.…”