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There are many compound semiconductors which can be prepared in only one conductivity type or another due to thermodynamic limitations. GaN one such material.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
70% of the total text.
Page 1 of 1
Method To Change Resistivity Type Of Semiconductors
There are many compound semiconductors which can be prepared in only
one conductivity type or another due to thermodynamic limitations. GaN one
GaN is a wide bandgap semiconductor (3.4 eV), which makes it quite useful
for optoelectronic applications. Many of its potential applications require that the
material be made both "p" and "n" type so that pn junctions can be fabricated.
However, in the case of GaN, only "n" type material has been made, and
attempts to dope to "p" type with Zn and Mg have failed to change the
conductivity significantly. GaN has a donor concentration of 10/-18/-10/19/cm/-
3/, and this is believed to be due to nitrogen vacancies. The attempted doping by
Zn or Mg has failed due to self-compensation.
A method is herein devised to provide, within the GaN lattice,
nitrogen in atomic form and then to react this atomic nitrogen very
rapidly so that the lattice does not have time to provide
self-compensation and phase separation of the excess nitrogen and
thereby return to the stable form, i.e., with nitrogen vacancies.
This scheme is accomplished by a two step process:
1. ion implant atomic nitrogen to greater than 10/18/cm/-3/
2. laser anneal to react the N with the N vacancies.
The laser annealing will eliminate the lattice damage due to
ion implantation and activate the N atoms to occupy the vacant sites.
Of critical importance is the speed of laser annealing which can