TCT investigation of the one-sided depletion of low-temperature covalently bonded silicon sensor P-N diodes

TL;DR

This paper investigates the asymmetric depletion behavior of low-temperature covalently bonded silicon P-N diodes using transient current technique, revealing that only the P-side depletes under reverse bias, which impacts sensor performance.

Contribution

It provides a detailed TCT analysis and custom setup for studying depletion in bonded silicon P-N diodes, highlighting the asymmetric depletion phenomenon.

Findings

Bonded P-N diodes show asymmetric depletion behavior.

Only the P-side of the diode is depleted under reverse bias.

TCT measurements confirm the asymmetric depletion pattern.

Abstract

In the context of particle detectors, low-temperature covalent wafer-wafer bonding allows for integration of high-Z materials as absorbing layers with readout chips produced in standard CMOS processes. This enables for instance the fabrication of novel highly efficient X-ray imaging sensors. In order to investigate the effects of the covalent bonding on the signal generated in such sensors, wafer-wafer bonded silicon-silicon P-N pad diodes have previously been produced. The behaviour of these test samples is being investigated with transient current technique (TCT) measurements. In this paper we present an overview of the TCT setup as well as a custom sandwich-type sample holder used for these measurements. A review of the results presented in a previous paper shows, that the bonded P-N structures show a highly asymmetric depletion behaviour under reverse bias. IR edge TCT measurements confirm that only the P-side of the samples is being depleted.