Paper 2003-02
Investigation
of 4H SiC Schottky diodes by ion and x-ray micro beam induced charge collection
techniques
Diamond and Related Materials 12 (2003)
667-671 |
C Manfredotti*1,2,
E Vittone1,2, C Paolini1,2, P.Olivero1,2, A Lo Giudice2, M Jaksic3, R Barrett
4 |
1
Experimental Physics Department, University of
Torino, Torino, Italy 2
INFM (National Institute for Matter Physics), UdR
Torino-University, Torino, Italy 3
Experimental Physics Department,, Ruđer
Bošković Institute, Zagreb, Croatia 4 European Synchrotron Radiation facility (ESRF), BP 220, F-38043 Grenoble (France) |
Keywords: silicon
carbide, electrical properties characterization, electrical properties,
detectors |
Abstract
Silicon carbide has recently emerged as an attractive material for
ionisation radiation detection. The high band gap and high radiation damage resistance
should allow the fabrication of detectors capable to operate at high
temperature and in high radiation fields. The development of SiC radiation
detectors in the field of spectroscopy imposes severe constraints in the
electronic quality and in homogeneity of the material.
In this work we present an investigation of the charge collection
properties of “detector grade” 4H-SiC
Schottky diodes performed by means of the and X-ray and Ion Beam Induced Charge
Collection (XBICC and IBIC) techniques. Such techniques allow the minority
carrier diffusion length of the material to be evaluated and mapping of the
transport properties to be performed with a spatial resolution of the order of
1 micrometer.
The investigated detectors are formed by Schottky contact (Au) on the
epitaxial layer and an ohmic contact on the back side of 4H-SiC substrates.
IBIC measurements were performed using protons of energy 0.7 – 1.7 MeV.
The IBIC spectra show a complete charge collection generated by ionisation in
the depletion region. Similar analysis was also performed in steady state
conditions using data from photocurrent measurements carried out at ESRF using
3 keV photons.
IBIC and XBICC maps were obtained by recording the mean pulse height and
the mean photocurrent as a function of the photon or ion impact co-ordinates.
The analysis of such maps allowed us to individuate the spatial distribution of
defects and contact imperfections.