Semiconductor Characterization by Scanning Ion Beam Induced Charge (IBIC) Microscopy

Ettore Vittone

doi:10.1155/2013/637608

Abstract

The ion beam induced charge (IBIC) technique is a scanning microscopy technique which uses finely focused MeV ion beams as probes to measure and image the transport properties of semiconductor materials and devices. Its success stems from the combination of three main factors: the first is strictly technical and lies in the availability of laboratories and expertise around the world to provide scanning MeV ion beams focused down to submicrometer spots. The second reason stems from the peculiarity of MeV ion interaction with matter, due to the ability to penetrate tens of micrometers with reduced scattering and to excite a high number of free carriers to produce a measurable charge pulse from each incident ion. Last, but not least, is the availability of a robust theoretical model able to extract from the measurements all the parameters for an exhaustive characterization of the semiconductor. This paper is focused on these two latter issues, which are examined by reviewing the current status of IBIC by a comprehensive survey of the theoretical model and remarkable examples of IBIC applications and of ancillary techniques to the study of advanced semiconductor materials and devices.

Highlights

But not least, is the availability of a robust theoretical model able to extract from the measurements all the parameters for an exhaustive characterization of the semiconductor. is paper is focused on these two latter issues, which are examined by reviewing the current status of ion beam induced charge (IBIC) by a comprehensive survey of the theoretical model and remarkable examples of IBIC applications and of ancillary techniques to the study of advanced semiconductor materials and devices
Erefore, the ion undergoes a huge number of interactions and gradually loses its kinetic energy: the net effect is a gradual decrease of its velocity until the particle is stopped. e range of MeV light ions in matter is mainly determined by the electron stopping power and depends on both the ion and target masses, atomic number, and ion velocity; for MeV
Many laboratories equipped with microfocused MeV ion beams have carried out IBIC experiments for the characterization of basic devices as Schottky, p-n, or MOS diodes as well as of dosimeters, particle detectors, or LEDs [107]. e reason of the widespread use of this technique resides in the availability of tens of high energy microprobes around the world, the widespread expertise on handling and processing charge pulses, commonly used in nuclear spectroscopy, and the possibility of a synergetic coupling with other ion beam analytical (IBA) techniques such as particle induced X-ray emission (PIXE), IBIL, and scanning ion transmission microscopy (STIM) [108]

Summary

Introduction

A charged particle with energy higher than 10 eV (i.e., charged particulate ionizing radiation) passing through a material deposits energy mainly through Coulomb interactions with the electrons within the absorber atoms [1,2,3]. The interaction of a single MeV ion with a semiconductor material generates a high-density volume of free carriers along the ion trajectory, which is nearly a straight line, with a typical energy-loss pro le, known as Bragg curve, peaked at the end of the ion range. The knowledge of the ion strike position combined with the almost straight ion trajectory, the large analytical depth, which can be modulated as function of ion energy and mass and the submicrometer radial extent of the charge carrier generation volume, allows the electronic features of semiconductors to be spatially resolved at the micrometer level. Is paper focuses on some theoretical aspects, which are needful to provide solid interpretations of IBIC experiments and remarkable examples of electronic characterization of important semiconductor materials

Charge Induction and Signal Formation

Ion Beam Induced Charge Microscopy

MeV proton beam

Conclusions