Abstract
Al
0.26
Ga
0.74
N
∕
Al
N
∕
Ga
N
heterostructures with
1
-
nm
-thick AlN interfacial layers were grown on
100
-
mm
-diam epitaxial AlN/sapphire templates and sapphire substrates by metalorganic vapor phase epitaxy. It was found that AlN/sapphire templates significantly enhanced the electron mobility of the two-dimensional electron gas (2DEG) confined at the GaN channel. This can be explained by the high-crystal-quality GaN channel realized by the use of epitaxial AlN/sapphire templates as substrates. The very high Hall mobilities of approximately
2100
cm
2
∕
V
s
at room temperature and approximately
17
000
cm
2
∕
V
s
at
77
K
with a 2DEG density of approximately
1
×
10
13
∕
cm
2
were uniformly obtained for
Al
Ga
N
∕
Al
N
∕
Ga
N
heterostructures on
100
-
mm
-diam epitaxial AlN/sapphire templates. The Hall mobility of
Al
Ga
N
∕
Al
N
∕
Ga
N
heterostructures on epitaxial AlN/sapphire templates reached a very high value of
25
500
cm
2
∕
V
s
at
15
K
.