Elsevier

Microelectronic Engineering

Volumes 43–44, 1 August 1998, Pages 107-111
Microelectronic Engineering

Low temperature transport properties of InAs/GaAs structures with quantum dots

https://doi.org/10.1016/S0167-9317(98)00228-7Get rights and content

Abstract

The transport and optical properties of InAs/GaAs structures with quantum dots have been investigated as a function of InAs content. Photoluminescence (PL) spectra showed polarization of radiation in the plane of the structures. The temperature dependence of the resistance was measured in the [110] and [−110] directions in the temperature range 4.2 K–300 K and anisotropy of conductivity was found. The Shubnikov de Haas effect, magnetoresistance ρ(B) and the Hall effect have been measured in a magnetic field B up to 10 T.

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.

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