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85 DEFECT CHARACTERIZATION BY JUNCTION SPECTROSCOPY

L. C. KIMERLING Bell Laboratories, Murray Hill, New Jersey

07974

ABSTRACT Junction spectroscopic techniques provide a unique tool for the study of imperfections in semiconductor materials. New, fundamental defect processes have been discovered and direct observations of the role of defects in device manufacture and operation have been made. The principles of application of capacitance transient spectroscopy, electroluminescence, and SEM-charge collection microscopy are briefly reviewed. Examples of singular accomplishments of these techniques are given, and directions of future research are outlined. INTRODUCTION A new class of material characterization techniques has evolved during the past decade which utilizes semiconductor junctions as the test device. The application of these methods has led to the discovery of new phenomena and provided a unique tool for the understanding of materials processing for semiconductor devices. The test specimens consist of Schottky barrier, p-n junction, or MOS structures - the standard building blocks of solid state circuitry. The characterization techniques are known as capacitance transient spectroscopy, SEMcharge collection microscopy, and electroluminescence. These methods, as schematically illustrated in Figure 1, form a cross correlated set of diagnostics for characterization of the electrical and optical properties of defects in semiconductors. This paper will briefly review the physical principles underlying these techniques and highlight some current materials research applications with both fundamental and applied implications. Each section concludes with directions for future research. SEMICONDUCTOR JUNCTIONS The relevant properties of abrupt, semiconductor junctions are outlined below. [The physics of semiconductor junction devices are discussed in books by Sze [1] and Moll [21.1 The junction is defined as the boundary across which the majority carrier changes sign and changes density by more than a factor of ten. Figures 1 and 2 and the relations below refer to an n-type substrate. CTS

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