We describe the realization of buried-heterostructure quantum-cascade lasers (QCLs) using gas-source molecular beam epitaxy both for the growth of the active region as well as for the regrowth of InP:Fe. The regrowth of the semi-insulating InP:Fe layer was carried out at 470 °C, which is more than 100 °C below the standard growth temperature during metal-organic vapor-phase epitaxy, the standard method for laser overgrowth. The electrical resistivity of the InP:Fe insulation layer, measured in test samples grown on (001) InP, is as large as 2×108Ωcm. High-resistivity InP:Fe is overgrown non-selectively over the etched laser ridge, followed by the top contact alloyed through it to the active region. The processed quantum-cascade lasers show no evidence of parallel leakage current and exhibit lower threshold current density than lasers using SiO2 as an insulator. The ability to fabricate buried heterostructure lasers without exceeding 600 °C is important for strain-compensated AlAs-InGaAs quantum cascade lasers with large internal strain because these devices do not typically withstand temperatures used to grow InP:Fe using vapor-phase epitaxy.

1.
J.
Faist
,
F.
Capasso
,
D. L.
Sivco
,
C.
Sirtori
,
A. L.
Hutchinson
, and
A. Y.
Cho
,
Science
264
,
553
(
1994
).
2.
C.
Gmachl
,
F.
Capasso
,
D. L.
Sivco
, and
A. Y.
Cho
,
Rep. Prog. Phys.
64
,
1533
(
2001
).
3.
M.
Beck
,
J.
Faist
,
C.
Gmachl
,
F.
Capasso
,
D. L.
Sivco
,
J. N.
Baillargeon
, and
A. Y.
Cho
,
Proc. SPIE
3284
,
231
(
1998
).
4.
M.
Beck
,
J.
Faist
,
U.
Oesterle
,
M.
Ilegems
,
E.
Gini
, and
H.
Melchior
,
IEEE Photon. Technol. Lett.
12
,
1450
(
2000
).
5.
M.
Beck
,
D.
Hofstetter
,
Th.
Aellen
,
J.
Faist
,
U.
Oesterle
,
M.
Ilegems
,
E.
Gini
, and
H.
Melchior
,
Science
295
,
301
(
2002
).
6.
A.
Evans
,
J. S.
Yu
,
J.
David
,
L.
Doris
,
K.
Mi
,
S.
Slivken
, and
M.
Razeghi
,
Appl. Phys. Lett.
84
,
314
(
2004
).
7.
M.
Troccoli
,
S.
Corzine
,
D.
Bour
,
J.
Zhu
,
O.
Assayag
,
L.
Diehl
,
B. G.
Lee
,
G.
Hfler
, and
F.
Capasso
,
Electron. Lett.
41
,
1059
(
2005
).
8.
L.
Diehl
,
D.
Bour
,
S.
Corzine
,
J.
Zhu
,
G.
Hfler
,
M.
Lončar
,
M.
Troccoli
, and
F.
Capasso
,
Appl. Phys. Lett.
88
,
201115
(
2006
).
9.
L.
Diehl
,
D.
Bour
,
S.
Corzine
,
J.
Zhu
,
G.
Hfler
,
M.
Lončar
,
M.
Troccoli
, and
F.
Capasso
,
Appl. Phys. Lett.
89
,
081101
(
2006
).
10.
A.
Evans
,
S. R.
Darvish
,
S.
Slivken
,
J.
Nguyen
,
Y.
Bai
, and
M.
Razeghi
,
Appl. Phys. Lett.
91
,
071101
(
2007
).
11.
M. P.
Semtsiv
,
M.
Ziegler
,
S.
Dressler
,
W. T.
Masselink
,
N.
Georgiev
,
T.
Dekorsy
, and
M.
Helm
,
Appl. Phys. Lett.
85
,
1478
(
2004
).
12.
M. P.
Semtsiv
,
M.
Wienold
,
S.
Dressler
, and
W. T.
Masselink
,
Appl. Phys. Lett.
90
,
051111
(
2007
).
13.
D. G.
Revin
,
J. W.
Cockburn
,
M. J.
Steer
,
R. J.
Airey
,
M.
Hopkinson
,
A. B.
Krysa
,
L. R.
Wilson
, and
S.
Menzel
,
Appl. Phys. Lett.
91
,
051123
(
2007
).
14.
Y.
Bai
,
N.
Bandyopadhyay
,
S.
Tsao
,
E.
Selcuk
,
S.
Slivken
, and
M.
Razeghi
,
Appl. Phys. Lett.
97
,
251104
(
2010
).
15.
A.
Bismuto
,
M.
Beck
, and
J.
Faist
,
Appl. Phys. Lett.
98
,
191104
(
2011
).
16.
To address the thermal degradation of heavily strained (but strain compensated) QCLs including AlAs barriers, we have annealed pieces of the same AlAs-InGaAs QCL wafer, similar to published in Ref. 11 in an MBE chamber for one hour at the temperatures of 550 °C (approximately the upper temperature limit for InP growth by MBE) and 650 °C (typical MOVPE growth temperature for InP). The surface of the wafer peaces was protected from thermal decomposition by 100 nm SiO2, deposited by reactive magnetron sputtering. After annealing, the wafer pieces processed into lasers and characterized in terms of threshold current densities at room temperature. As-grown and annealed at 550 °C samples have shown the same resistivity and threshold current densities. The sample annealed at 650 °C had low resistance and did not lase even at cryogenic temperatures. Details of the annealing experiment are to be published elswhere. This test indicates that heavily strained AlAs-InGaAs QCLs do not withstand the MOVPE-based BH QCL fabrication and require a different method.
17.
S.
Slivken
,
C.
Jelen
,
A.
Rybaltowski
,
J.
Diaz
, and
M.
Razeghi
,
Appl. Phys. Lett.
71
,
2593
(
1997
).
18.
M.
Lambert
,
L.
Goldstein
,
A.
Perales
,
F.
Gaborit
,
Ch.
Starck
, and
J.-L.
Lievin
,
J. Cryst. Growth
111
,
495
(
1991
).
19.
Ph.
Pagnod-Rossiaux
,
M.
Lambert
,
F.
Gaborit
,
F.
Brillouet
,
P.
Garabedian
, and
L.
Le Gouezigou
,
J. Cryst. Growth
120
,
317
(
1992
).
20.
W.
Shockley
and
R. C.
Prim
,
Phys. Rev.
90
,
753
(
1953
).
21.
J.
Faist
,
D.
Hofstetter
,
M.
Beck
,
T.
Aellen
,
M.
Rochat
, and
S.
Blaser
,
IEEE J. Quantum Electron.
38
,
533
(
2002
).
22.
The trade-off between the thermal conductivity and optical confinement (i.e., optimization of the thickness of InGaAs layer around the active region) is an important aspect of the laser design and requires a separate study.
You do not currently have access to this content.