ISO 5618-1:2023

INTERNATIONAL ISO
STANDARD 5618-1
First edition
2023-11
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Test method for GaN crystal surface
defects —
Part 1:
Classification of defects
Céramiques techniques — Méthode d’essai pour les défauts de surface
des cristaux de GaN —
Partie 1: Classification des défauts
Reference number
© ISO 2023
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification of defects . 3
4.1 General . 3
4.2 Description of the defect classes . 3
4.2.1 Dislocation . 3
4.2.2 Process-induced defects . 5
Bibliography . 7
iii
Foreword
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iv
Introduction
GaN is a direct transition type of wide-bandgap semiconductor with superior physical properties,
including a higher breakdown electric field, saturated electron drift velocity and thermal conductivity,
to Si. GaN is expected to be applied not only in light-emitting devices that have been in practical use
for a long time, such as ultraviolet and blue laser diodes (LDs) and light-emitting diodes (LEDs), but
also in power devices for high-efficiency power conversion. In particular, the characteristics of GaN-
based power devices are applied in the fields of photovoltaics, automobiles, railways (electric motors
and linear motors), communication base stations and microwave power transmission.
The single-crystal GaN substrate or single-crystal GaN film is the base material used to produce
devices. However, the surface of a single-crystal GaN substrate or single-crystal GaN film contains
many dislocations that are introduced during crystal growth and defects that are introduced during
wafer processing. The dislocations and/or defects cause a decrease in luminous efficiency for a light-
emitting device and a degradation in performance and reliability for a power device. In particular,
given the practical applications and market expansion of power devices that apply a high voltage and
high current, it is important to supply single-crystal GaN substrates and single-crystal GaN films with
low densities of dislocation and defects. Therefore, it is essential to have an International Standard that
defines and classifies the types of, and further determines the density of, dislocations and process-
induced defects that exist on the surface as an index for assessing the quality of a single-crystal GaN
substrate or single-crystal GaN film.
This document gives a classification of the dislocations and process-induced defects exposed on the
surface of single-crystal GaN substrates and single-crystal GaN films. These single-crystal substrates
and films are mainly used for light-emitting devices, such as LDs and LEDs, and power devices
1)
that perform high-voltage and high-current power conversion. ISO 5618-2 provides a method of
determining the etch pit density.
1) Under preparation. Stage at the time of publication: ISO/DIS 5618-2:2023.
v
INTERNATIONAL STANDARD ISO 5618-1:2023(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for GaN crystal surface defects —
Part 1:
Classification of defects
1 Scope
This document gives a classification of the dislocations and process-induced defects, from among the
various surface defects, that occur on single-crystal gallium nitride (GaN) substrates or single-crystal
GaN films.
It is applicable to the dislocations and process-induced defects exposed on the surface of the following
types of GaN substrates or films:
— single-crystal GaN substrate;
— single-crystal GaN film formed by homoepitaxial growth on a single-crystal GaN substrate;
— single-crystal GaN film formed by heteroepitaxial growth on a single-
...