TY - JOUR
T1 - Characteristics of deep-well 4.8 μm-emitting quantum-cascade lasers grown by MOCVD
AU - Shin, J. C.
AU - D'Souza, M.
AU - Xu, D.
AU - Kirch, J.
AU - Mawst, L. J.
AU - Botez, D.
AU - Vurgaftman, I.
AU - Meyer, J. R.
PY - 2009
Y1 - 2009
N2 - In this work we present the characteristics of a novel type of quantum-cascade (QC) laser: the deep-well (DW) QC device, which, unlike conventional QC lasers, contains a superlattice of quantum wells and barriers of different composition, respectively. The fabrication of DW-QC devices is made possible by the use of metal-organic chemical vapor deposition (MOCVD), a crystal growth technique which allows one to easily vary the composition of wells and barriers within QC structures, thus providing significantly increased flexibility in optimizing the device design. We have designed such varying-composition QC structures to have deep quantum wells in and tall barriers in and around the active region. DW- QC laser structures have fabricated into 19 μm wide ridges and 3 mm-long chips. Threshold-current densities as low as 1.5 kA/cm 2 are obtained at room temperature in the 4.6-4.8 μm wavelength region. In conventional QC lasers emitting in the 4.5-5.5μm range there is substantial thermionic carrier leakage from the upper laser level to the continuum, as evidenced by a significant decrease in the slope efficiency above 250 K, which is understandable given the relatively small (i.e., ∼ 200 meV) energy differential, δE, between the upper lasing level and the top of the exit barrier. For the DW design carrier leakage is suppressed due to deep active wells and tall barriers, such that δE reaches values in excess of 400 meV. Preliminary results include a threshold-current characteristic temperature, T 0, value of 218 K over the temperature range: 250- 340 K.
AB - In this work we present the characteristics of a novel type of quantum-cascade (QC) laser: the deep-well (DW) QC device, which, unlike conventional QC lasers, contains a superlattice of quantum wells and barriers of different composition, respectively. The fabrication of DW-QC devices is made possible by the use of metal-organic chemical vapor deposition (MOCVD), a crystal growth technique which allows one to easily vary the composition of wells and barriers within QC structures, thus providing significantly increased flexibility in optimizing the device design. We have designed such varying-composition QC structures to have deep quantum wells in and tall barriers in and around the active region. DW- QC laser structures have fabricated into 19 μm wide ridges and 3 mm-long chips. Threshold-current densities as low as 1.5 kA/cm 2 are obtained at room temperature in the 4.6-4.8 μm wavelength region. In conventional QC lasers emitting in the 4.5-5.5μm range there is substantial thermionic carrier leakage from the upper laser level to the continuum, as evidenced by a significant decrease in the slope efficiency above 250 K, which is understandable given the relatively small (i.e., ∼ 200 meV) energy differential, δE, between the upper lasing level and the top of the exit barrier. For the DW design carrier leakage is suppressed due to deep active wells and tall barriers, such that δE reaches values in excess of 400 meV. Preliminary results include a threshold-current characteristic temperature, T 0, value of 218 K over the temperature range: 250- 340 K.
KW - Characteristic temperature of threshold current
KW - Mid-infrared
KW - Quantum cascade laser
KW - Strain-compensated
UR - http://www.scopus.com/inward/record.url?scp=63449106501&partnerID=8YFLogxK
U2 - 10.1117/12.808268
DO - 10.1117/12.808268
M3 - Conference article
AN - SCOPUS:63449106501
SN - 0277-786X
VL - 7230
JO - Proceedings of SPIE - The International Society for Optical Engineering
JF - Proceedings of SPIE - The International Society for Optical Engineering
M1 - 723013
T2 - Novel In-Plane Semiconductor Lasers VIII
Y2 - 26 January 2009 through 29 January 2009
ER -