Low temperature transport properties of InAs/GaAs structures with quantum dots
Introduction
Nanoscale structures such as quantum dots are very interesting from the physics and device application viewpoints. The strain induced formation of small InAs islands during the heteroepitaxial growth of InAs on GaAs substrate represents the efficient way of producing quantum dots with electronic confinement in all three directions. While the optical properties of such quantum dot structures are being investigating now with high intensity, the transport properties of these quantum dot structures have not been yet investigated. In the present work the results of investigation of photoluminescence and low temperature transport properties of InAs/GaAs quantum dot structures are reported.
Section snippets
Experimental
The structures were grown by atmosphere pressure MOSVD at 630°C from trimethylindium, trimetilgallium, and arsine in semiinsulating (001) GaAs substrates misoriented 3° from the (001) plane forward to the [110] direction. The samples consisted of several periods (10–20) of GaAs 0.1 μm, delta-layer with doping impurity (for p-type samples), 5–6 nm spacer, InAs quantum dots (QDs) layer. On the top of structures a cap layer (0.1 μm layer GaAs) was deposited. The n-type samples was undoped. Some
Results and discussion
The QD size 6–7 nm was obtained from the maximum of PL spectra using the theory developed in Ref. 2, 3. The semiwidth of the PL spectra at 77 K (20–60 meV) showed scattering of the QD sizes. The observed maximal value in photoluminescence peak was 1.34–1.41 eV for n-type samples and 1.28–1.41 eV for p-type samples (Table 1, Fig. 1, Fig. 2). Photoluminescence spectra showed polarization of emitted light in the plane of the structures (see Fig. 1). The nature of the polarization is unknown now.
Conclusions
The magnetoresistance oscillations and their angle dependence on magnetic field direction shows the presence of two dimensional electrons (holes) in the investigated structures. The resistance and its temperature dependence in investigated quantum dot structures showed an anisotropy due to formation of quantum dot chains along the [−110] direction. Photoluminescence spectra showed polarization of emitted light in the plane of the structures.
References (4)
- et al.
JETP Lett.
(1996) - et al.
Phys. Rev. Lett.
(1994)
Cited by (3)
Persistent infrared photoconductivity in InAs/GaAs structures with quantum dot layer
2007, Physica E: Low-Dimensional Systems and NanostructuresPersistent IR photoconductivity in InAs/GaAs structures with QD layers
2006, SemiconductorsQuantum hall effect-insulator transition in the InAs/GaAs system with quantum dots
2003, Physics of the Solid State