Ultra-high-k SrTiO3 hole blocking layer for low excess noise solid-state amorphous selenium avalanche detector

Background

The photo‑detecting device industry is searching for a solid‑state alternative to the vacuum photomultiplier. Research has shown that amorphous selenium based solid‑state avalanche detectors are promising candidates that can provide gains comparable to photomultiplier tubes (106) at low cost. However, a significant limitation to their development is inefficient hole blocking layers, which lead to irreversible dielectric breakdown at high electric fields. Thus, the industry seeks a practical alternative which has large‑area detection, high dynamic range, linear‑mode operation, and low noise avalanche gain to compete with conventional vacuum photomultipliers as well as traditionally used silicon avalanche photodiodes.

Technology

Researchers at Stony Brook University (SBU) propose a low‑noise amorphous selenium based solid‑state avalanche detector that uses strontium titanate (SrTiO3) as the high‑k dielectric hole‑blocking n‑layer. The high‑k non‑insulating strontium titanate layer substantially decreases the electric field at the HBL/high‑voltage‑metal‑electrode interface. This limits Schottky injection from the high voltage electrode, thus preventing Joule heating from crystallizing the amorphous selenium layer, which further avoids irreversible dielectric breakdown of the device. This structure, at a substantially lower cost compared to crystalline silicon, provides reliable and repeatable impact ionization gain with low excess noise, high dynamic range, linear‑mode operation, and ultra‑low dark current at room temperature.

Advantages

Low‑cost - Low excess noise - High dynamic range - Linear‑mode operation - Ultra‑low leakage current at high fields - Stable at room temperature / Does not require cooling