IBIC characterization of an ion-beam-micromachined multi-electrode diamond detector

TL;DR

This paper reports on the development and detailed characterization of a diamond-based ionization detector with buried electrodes fabricated via deep ion beam lithography, highlighting its charge collection efficiency and the effects of fabrication-induced dead layers.

Contribution

It introduces a novel fully ion-beam-micromachined diamond detector with interdigitated electrodes and provides comprehensive IBIC-based performance analysis.

Findings

Charge collection efficiency maps reveal detailed detector behavior.

Electrons and holes contribute differently to induced charge pulses.

Dead layer formation affects detector performance.

Abstract

Deep Ion Beam Lithography (DIBL) has been used for the direct writing of buried graphitic regions in monocrystalline diamond with micrometric resolution. Aiming at the development and the characterization of a fully ion-beam-micromachined solid state ionization chamber, a device with interdigitated electrodes was fabricated by using a 1.8 MeV He+ ion microbeam scanning on a homoepitaxial, grown by chemical vapour deposition (CVD). In order to evaluate the ionizing-radiation-detection performance of the device, charge collection efficiency (CCE) maps were extracted from Ion Beam Induced Charge (IBIC) measurements carried out by probing different arrangements of buried microelectrodes. The analysis of the CCE maps allowed for an exhaustive evaluation of the detector features, in particular the individuation of the different role played by electrons and holes in the formation of the induced charge pulses. Finally, a comparison of the performances of the detector with buried graphitic electrodes with those relevant to conventional metallic surface electrodes evidenced the formation of a dead layer overlying the buried electrodes as a result of the fabrication process.