| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
|
| Symposium
|
2011 Electronic Materials Conference
|
| Presentation Title |
R2, Strain-Engineered Binary and Ternary Type-II Superlattice Structures and Photodiodes Grown by Metalorganic Chemical Vapor Deposition |
| Author(s) |
Yong Huang, Jae-Hyun Ryou, Russell Dupuis, Elizabeth Steenbergen, Jin Fan, Yong-Hang Zhang, Daniel Zuo, Ben Kesler, Adam Petschke, Martin Mandl, Shun-Lien Chuang, Hefei Hu, Kyohyun Kim, Yen-Ting Lu, Jian-Min Zuo |
| On-Site Speaker (Planned) |
Jae-Hyun Ryou |
| Abstract Scope |
Type-II superlattice (T2SL) structures containing III-Sb alloys have been exploited as photodetectors operating in a wide range of the infrared (IR) spectral region covering from mid-IR to very-long-wavelength-IR. Although there are several approaches to T2SL photodetector design, recent research efforts have been focused on InAs/GaSb strained T2SL on GaSb substrates employing InSb-like interfacial (IF) layers grown by molecular beam epitaxy (MBE). Such an InSb-like IF layer used in MBE for strain balancing cannot be easily adopted in metalorganic chemical vapor deposition (MOCVD). In order to develop T2SL-based photodetectors grown by MOCVD, new approaches for strain balancing in T2SLs structures are required. In this study, we report on the characterization of several T2SL epitaxial structures with a focus on strain balancing. The structures include: (1) InAs/GaSb SLs on GaSb with various IF layers; (2) InAs/InAs<sub>1-x</sub>Sb<sub>x</sub> SLs on GaSb; and (3) InAs/GaSb SLs on InAs. During growth of the InAs/GaSb SLs by MOCVD, the gas switching sequence and IF layer control are of critical importance. InAsSb and InGaSb IF layers are introduced to compensate the tensile strain and hence to improve the overall material quality of the SL structures. As suggested by the X-ray diffraction (XRD) and atomic force microscopy (AFM) results, the optimal morphology and lowest strain are achieved via a combined IF layer scheme with 1 monolayer (ML) InAsSb + 1 ML InGaSb layers. RMS (root-mean square) surface roughness is ~0.172 nm and the separation between the SL 0th-order peak and the substrate is ~448 arcsec., corresponding to an in-plane lattice mismatch of ~0.17%. In the case of InAs/InAs<sub>1-x</sub>Sb<sub>x</sub> SLs on GaSb, the strain-balancing can be achieved by employing a ternary layer and simple precursor flow switching scheme. Excellent surface morphology with a RMS surface roughness value as low as ~0.108 nm is obtained. XRD ω-2θ scans exhibit narrow and intense satellite peaks, indicating superior structural quality and sharp interfaces. The average in-plane strains are only ~0.07 % and ~0.02 %, which indicate that the SLs are nearly strain-balanced. In addition, as shown in a comparative study of experimental and simulation XRD curves, under certain growth conditions, the InAs/GaSb SLs can be grown without any intentional IF layer, and data suggest the existence of an additional tensile-strained layer, which is believed to be a 1-ML-thick GaAs. While this additional layer is detrimental in strain balancing on GaSb substrates, it is beneficial on InAs substrates. The strain engineering of InAs/GaSb SLs on InAs is under further investigation and the latest results will be reported. In summary, the structural and optical properties of various MOCVD-grown T2SLs are studied and <i>p-i-n</i> photodiodes employing these T2SLs and T2SL photodetectors are demonstrated and described. |
| Proceedings Inclusion? |
Undecided |