Metal-assisted chemical etching is a plasma-free open-circuit anisotropic etching method that produces high aspect ratio structures in various semiconductors. Here, for the first time, we demonstrate the formation of ordered micropillar arrays of homoepitaxial GaN, using photo-enhanced MacEtch with patterned platinum films as the catalyst. The GaN etching rate and morphology as a function of etching chemistry, growth method, and doping conditions are investigated, and the etch mechanism is analyzed. Etch rates and surface smoothness are found to increase with the Si-doping level in GaN, approaching those achieved by reactive ion etching and photoelectrochemical etching. Spatially resolved photoluminescence shows no degradation in near band edge emission and no newly generated defect peaks, as expected due to the high energy ion free nature. This approach can also potentially be applied to InGaN and AlGaN by tuning the etch chemistry and illumination wavelength, enabling a facile and scalable processing of 3D III-nitride based electronic and optoelectronic devices such as μLEDs and finFETs.

1.
X.
Liu
,
Y.
Wu
,
Y.
Malhotra
,
Y.
Sun
,
Y.
Ra
,
R.
Wang
,
M.
Stevenson
,
S.
Coe-Sullivan
, and
Z.
Mi
,
J. Soc. Inf. Disp.
28
,
410
(
2020
).
2.
J. Y.
Lin
and
H. X.
Jiang
,
Appl. Phys. Lett.
116
,
100502
(
2020
).
3.
J.
Zhu
,
X.
Zhou
,
L.
Jing
,
Q.
Hua
,
W.
Hu
, and
Z. L.
Wang
,
ACS Nano
13
,
13161
(
2019
).
4.
Y.
Zhang
 et al.,
IEEE Electron Device Lett.
40
,
75
(
2019
).
5.
S.
Li
and
A.
Waag
,
J. Appl. Phys.
111
,
071101
(
2012
).
6.
I. M.
Høiaas
,
A.
Liudi Mulyo
,
P. E.
Vullum
,
D. C.
Kim
,
L.
Ahtapodov
,
B. O.
Fimland
,
K.
Kishino
, and
H.
Weman
,
Nano Lett.
19
,
1649
(
2019
).
7.
F.
Yu
 et al.,
Appl. Phys. Lett.
108
,
213503
(
2016
).
8.
Q.
Fan
,
S.
Chevtchenko
,
X.
Ni
,
S.-J.
Cho
,
F.
Yun
, and
H.
Morkoç
,
J. Vac. Sci. Technol. B
24
,
1197
(
2006
).
9.
Z.
Mouffak
,
A.
Bensaoula
, and
L.
Trombetta
,
J. Semicond.
35
,
113003
(
2014
).
10.
M. S.
Wong
,
D.
Hwang
,
A. I.
Alhassan
,
C.
Lee
,
R.
Ley
,
S.
Nakamura
, and
S. P.
DenBaars
,
Opt. Express
26
,
21324
(
2018
).
11.
M. S.
Wong
,
C.
Lee
,
D. J.
Myers
,
D.
Hwang
,
J. A.
Kearns
,
T.
Li
,
J. S.
Speck
,
S.
Nakamura
, and
S. P.
Denbaars
,
Appl. Phys. Express
12
,
097004
(
2019
).
12.
M.
Kodama
 et al.,
Appl. Phys. Express
1
,
021104
(
2008
).
13.
Y.
Zhang
,
M.
Sun
,
Z.
Liu
,
D.
Piedra
,
J.
Hu
,
X.
Gao
, and
T.
Palacios
,
Appl. Phys. Lett.
110
,
193506
(
2017
).
14.
J.
Zhu
,
T.
Takahashi
,
D.
Ohori
,
K.
Endo
,
S.
Samukawa
,
M.
Shimizu
, and
X. L.
Wang
,
Phys. Status Solidi Appl. Mater. Sci.
216
, 1900380 (
2019
).
15.
X.
Li
,
Curr. Opin. Solid State Mater. Sci.
16
,
71
(
2012
).
16.
Z.
Huang
,
N.
Geyer
,
P.
Werner
,
J.
de Boor
, and
U.
Gösele
,
Adv. Mater.
23
,
285
(
2011
).
17.
X.
Li
and
P. W.
Bohn
,
Appl. Phys. Lett.
77
,
2572
(
2000
).
18.
S.-W.
Chang
,
V. P.
Chuang
,
S. T.
Boles
,
C. A.
Ross
, and
C. V.
Thompson
,
Adv. Funct. Mater.
19
,
2495
(
2009
).
19.
J. D.
Kim
,
P. K.
Mohseni
,
K.
Balasundaram
,
S.
Ranganathan
,
J.
Pachamuthu
,
J. J.
Coleman
, and
X.
Li
,
Adv. Funct. Mater.
27
,
1605614
(
2017
).
20.
J. D.
Kim
,
M.
Kim
,
C.
Chan
,
N.
Draeger
,
J. J.
Coleman
, and
X.
Li
,
ACS Appl. Mater. Interfaces
11
,
27371
(
2019
).
21.
A.
Mallavarapu
,
P.
Ajay
,
C.
Barrera
, and
S. V.
Sreenivasan
,
ACS Appl. Mater. Interfaces
13
,
1169
(
2021
).
22.
M.
DeJarld
,
J. C.
Shin
,
W.
Chern
,
D.
Chanda
,
K.
Balasundaram
,
J. A.
Rogers
, and
X.
Li
,
Nano Lett.
11
,
5259
(
2011
).
23.
L.
Kong
,
Y.
Song
,
J. D.
Kim
,
L.
Yu
,
D.
Wasserman
,
W. K.
Chim
,
S. Y.
Chiam
, and
X.
Li
,
ACS Nano
11
,
10193
(
2017
).
24.
S. H.
Kim
,
P. K.
Mohseni
,
Y.
Song
,
T.
Ishihara
, and
X.
Li
,
Nano Lett.
15
,
641
(
2015
).
25.
D. M.
Dryden
,
R. J.
Nikolic
, and
M. S.
Islam
,
J. Electron. Mater.
48
,
3345
(
2019
).
26.
Y.
Chen
,
C.
Zhang
,
L.
Li
,
S.
Zhou
,
X.
Chen
,
J.
Gao
,
N.
Zhao
, and
C.-P.
Wong
,
Small
15
,
1803898
(
2019
).
27.
F.
Horikiri
,
H.
Ohta
,
N.
Asai
,
Y.
Narita
,
T.
Yoshida
, and
T.
Mishima
,
Appl. Phys. Express
11
,
091001
(
2018
).
28.
J.
Murata
and
S.
Sadakuni
,
Electrochim. Acta
171
,
89
(
2015
).
29.
M. S.
Minsky
,
M.
White
, and
E. L.
Hu
,
Appl. Phys. Lett.
68
,
1531
(
1996
).
30.
C.
Youtsey
,
I.
Adesida
,
L. T.
Romano
, and
G.
Bulman
,
Appl. Phys. Lett.
72
,
560
(
1998
).
31.
J. A.
Bardwell
,
J. B.
Webb
,
H.
Tang
,
J.
Fraser
, and
S.
Moisa
,
J. Appl. Phys.
89
,
4142
(
2001
).
32.
A. C.
Tamboli
,
A.
Hirai
,
S.
Nakamura
,
S. P.
Denbaars
, and
E. L.
Hu
,
Appl. Phys. Lett.
94
,
151113
(
2009
).
33.
X.
Li
,
Y.-W.
Kim
,
P. W.
Bohn
, and
I.
Adesida
,
Appl. Phys. Lett.
80
,
980
(
2002
).
34.
R. J.
Shul
,
L.
Zhang
,
A. G.
Baca
,
C. G.
Willison
,
J.
Han
,
S. J.
Pearton
, and
F.
Ren
,
J. Vac. Sci. Technol. A
18
,
1139
(
2000
).
35.
Y.
Sun
,
X.
Kang
,
Y.
Zheng
,
K.
Wei
,
P.
Li
,
W.
Wang
,
X.
Liu
, and
G.
Zhang
,
Nanomaterials
10
,
657
(
2020
).
36.
C. H.
Chen
,
S. J.
Chang
,
Y. K.
Su
,
G. C.
Chi
,
J. K.
Sheu
, and
I. C.
Lin
,
Jpn. J. Appl. Phys.
40
,
2762
(
2001
).
37.
S.
Zhou
,
B.
Cao
, and
S.
Liu
,
Appl. Surf. Sci.
257
,
905
(
2010
).
38.
M.
Tautz
and
D.
DíazDíaz
,
ChemistrySelect
3
,
1480
(
2018
).
39.
C.
Zhao
,
X.
Zhang
,
C. W.
Tang
,
J.
Wang
, and
K. M.
Lau
,
J. Vac. Sci. Technol. B
38
,
060602
(
2020
).
40.
J. L.
Weyher
,
F. D.
Tichelaar
,
D. H.
van Dorp
,
J. J.
Kelly
, and
A.
Khachapuridze
,
J. Cryst. Growth
312
,
2607
(
2010
).
41.
K.
Watanabe
,
J. R.
Yang
,
S. Y.
Huang
,
K.
Inoke
,
J. T.
Hsu
,
R. C.
Tu
,
T.
Yamazaki
,
N.
Nakanishi
, and
M.
Shiojiri
,
Appl. Phys. Lett.
82
,
718
(
2003
).
42.
J. K.
Hite
,
T. J.
Anderson
,
L. E.
Luna
,
J. C.
Gallagher
,
M. A.
Mastro
,
J. A.
Freitas
, and
C. R.
Eddy
,
J. Cryst. Growth
498
,
352
(
2018
).
43.
See the supplementary material at https://www.scitation.org/doi/suppl/10.1116/6.0001231 for micropillar optical profiles, SEM images of etched HVPE substrates, FIB cross sections of etched HVPE samples, SEM images comparing etched MOCVD and HVPE samples, and additional PL data.

Supplementary Material

You do not currently have access to this content.