Chapter 8
III-Nitride LED Chip Fabrication
Techniques
With the development of epitaxial growth technology and multi-quantum well structure, the internal quantum efficiency of ultra-high brightness LED has been greatly
improved. For example, the internal quantum efficiency of the 625 nm AlGaInP-based
LED can reach almost 100%. However, defects caused by the lattice and thermal
mismatch, stress and electric field which present in GaN-based materials make the
internal quantum efficiency of Group III nitride (AlGaInN-based) LEDs relatively
low. For instance, a quantum efficiency typically in the range between 35 and 50% is
achieved. Therefore, increasing the external quantum efficiency of the LED chips is
the key to improve the luminous efficiency. This largely requires the proper designs
of a new chip structure to improve the light-emitting efficiency, thereby achieving
much enhanced luminous efficiency (or external quantum efficiency). In the development of III-nitride LED technology for semiconductor illumination, many technical
and theoretical issues including material epitaxy, p-doping and activation, material etching, ohmic contact, photoelectric characteristics, current spreading, lightemitting structure, and device protection are being solved or continuously advanced.
Mature theories and processes such as p-type GaN annealing activation, ICP etching
methods, heavily doped top layer preparation for ohmic contacts, electrode structures, etc. have become the standard in current laboratories and factories, driving the
science and technology of semiconductor lighting technology. The key fabrication
process of the III-nitride LED described in this chapter is a combination of the basic
fabrication process and the process technologies.
8.1 Group III Nitride LED Fabrication Process
Since sapphire is an insulator with very stable chemical and physical properties, the
p- and n-type electrodes of the GaN-based LED chip epitaxially grown on sapphire
substrates are located on the same side of the epitaxial structure. This structure is
© Science Press and Springer Nature Singapore Pte Ltd. 2020
J. Li et al., III-Nitrides Light Emitting Diodes: Technology and Applications,
Springer Series in Materials Science 306,
https://doi.org/10.1007/978-981-15-7949-3_8
151
III-Nitride LED Chip Fabrication
Techniques
With the development of epitaxial growth technology and multi-quantum well structure, the internal quantum efficiency of ultra-high brightness LED has been greatly
improved. For example, the internal quantum efficiency of the 625 nm AlGaInP-based
LED can reach almost 100%. However, defects caused by the lattice and thermal
mismatch, stress and electric field which present in GaN-based materials make the
internal quantum efficiency of Group III nitride (AlGaInN-based) LEDs relatively
low. For instance, a quantum efficiency typically in the range between 35 and 50% is
achieved. Therefore, increasing the external quantum efficiency of the LED chips is
the key to improve the luminous efficiency. This largely requires the proper designs
of a new chip structure to improve the light-emitting efficiency, thereby achieving
much enhanced luminous efficiency (or external quantum efficiency). In the development of III-nitride LED technology for semiconductor illumination, many technical
and theoretical issues including material epitaxy, p-doping and activation, material etching, ohmic contact, photoelectric characteristics, current spreading, lightemitting structure, and device protection are being solved or continuously advanced.
Mature theories and processes such as p-type GaN annealing activation, ICP etching
methods, heavily doped top layer preparation for ohmic contacts, electrode structures, etc. have become the standard in current laboratories and factories, driving the
science and technology of semiconductor lighting technology. The key fabrication
process of the III-nitride LED described in this chapter is a combination of the basic
fabrication process and the process technologies.
8.1 Group III Nitride LED Fabrication Process
Since sapphire is an insulator with very stable chemical and physical properties, the
p- and n-type electrodes of the GaN-based LED chip epitaxially grown on sapphire
substrates are located on the same side of the epitaxial structure. This structure is
© Science Press and Springer Nature Singapore Pte Ltd. 2020
J. Li et al., III-Nitrides Light Emitting Diodes: Technology and Applications,
Springer Series in Materials Science 306,
https://doi.org/10.1007/978-981-15-7949-3_8
151