Date/Time: 04-23-2019 - Tuesday - 05:00 PM - 07:00 PM
Shanthan Reddy Alugubelli1 Houqiang Fu2 Kai Fu2 Hanxiao Liu1 Yuji Zhao2 Fernando Ponce1

1, Arizona State University, Tempe, Arizona, United States
2, Arizona State University, Tempe, Arizona, United States

GaN is a material of interest for power electronics due to its high critical breakdown electric field of 3.3-3.75 MV/cm, compared to 0.3 MV/cm for silicon.A typical GaN-on-GaN power device has regions that are doped differently. For example, vertical-junction field-effect transistors (VJFET) have p-GaN region as the gate, intrinsic region as the drift layer, and the n-GaN region as the source and drain. Identifying these regions with a good spatial resolution is critical for the understanding of the device characteristics and failure analysis after malfunction. Dopant sensitive techniques like SIMS, electron holography are destructive and time consuming. Also, SIMS does not have the capability to resolve lateral variations in the layer design.
Low-voltage scanning electron microscopy has been used to study dopant contrast in GaN p-i-n epitaxial structures for power electronics applications. Secondary electron emission intensity is highest from p-layer and lowest from the unintentionally-doped (UID)-layer. Quantification of dopant contrast requires identification of all the parameters effecting the secondary electron emission intensity. In this work, we discuss about the factors effecting the secondary electron emission intensities from p-, i-, and n-type GaN layers. Also, we examine the effect of surface preparation on the dopant contrast. This technique is reliable for dopant profiling in GaN power electronics.

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