InAs/InGaAs/InP structures for quantum dot infrared photodetectors

Abstract

Self-assembled InAs quantum dots (QDs) over an InGaAs layer on InP substrates were grown by metalorganic chemical vapor deposition. Their structural and optical properties were investigated by atomic force microscopy and photoluminescence. Optimised stacks of structures were grown for a QD infrared photodetector and their absorption was measured. Magnetotransport measurements on the stacked QD structures revealed tunneling between quantum dot states with an applied magnetic field parallel to the current. 1 Introduction Infrared photodetectors based on intersubband transitions have received a great deal of attention for applications such as image recognition, atmospheric communications and toxic gas detection. In quantum well infrared photodetectors (QWIPs) the selection rules of the intersubband transitions prevent normal incident light from being absorbed [1]. To overcome this limitation, complex fabrication steps such as grating coupling is required [2]. On the other hand, quantum dot (QD) infrared photodetectors (QDIP) offer the prospect of normal incidence intersubband detection [3] due to the QD three dimensional character. Furthermore, QDIPs can have a broader infrared response range [4] and a higher responsivity due to the longer lifetime of excited electrons [5], which could also be exploited to increase the operating temperatures of these devices. However, for the QDIPs to replace the QWIPs a high density of dots is needed, as well as an uniform QD distribution. Multicolor [6,7] and high detectivity [5] QDIPs have been achieved recently for the mid-and the far-infrared ranges.Stacked self-assembled doped QDs form the QDIP structure. In particular, the so-called dot-in-a-well (DWELL) structure [8] is promising for QDIPs because the presence of a QW allows the bound-tobound transition from the ground state of the dot to a state in the well to be tuned by changing the QW thickness without modifying the QD structure.In recent years, there have been many studies of magnetotransport in self-assembled QDs, including magnetotunneling measurements to probe the electronic states of the quantum dots [9] and investigations of tunneling through double layers of stacked InAs dots [10]. However, so far there have been very few investigations on magnetotransport in stacked multi-layers of QDs, especially of magnetotunneling with the magnetic field applied parallel to the tunneling current.

Polarization Dependence of Photocurrent in InAs/InGaAs/InP Quantum-Dot Infared Photodetectors

“…The simple 1D model should predict with good accuracy the bound levels but some uncertainty is expected for the levels closer to the continuum. Perpendicular transport should occur via the QW E 2 level due to sequential resonant tunneling (16). It should be noted that the PC measurements presented in this article were taken at zero bias.…”

Morphology and Crystal Quality of InAs QDs Grown by MOVPE Using Different Growth Modes

“…Introduction: InAs/InP QDs systems have been investigated intensively because of their promising applications in ultra-low-loss optical fiber communications targeting at 1.55 µm emission wavelength [1]. On the other hand, InAs/InP QDs are expected to be able to emit in the midinfrared (IR), 2-4 µm, wavelength region by inserting InGaAs layer between InAs QDs and InP matrix, so promising for a variety of military, biomedical and environmental applications [2,3]. However, the InAs QDs grown on InGaAs/InP matrixes are generally with large morphology distribution due to the un-uniform strain relaxation of wetting layer and the anisotropic surface diffusion of In adatoms during the dots growth [ 4].…”

Formation of mid-infrared emissive InAs quantum dots on a graded InxGa1−xAs/InP matrix with a more uniform size and higher density under safer growth conditions

“…The low temperature photoluminescence spectrum of the QDs grown by the two-step growth has much narrower linewidth and higher intensity than that of the QDs grown by using normal Stranski-Krastanow (S-K) and atomic layer epitaxy (ALE) growth methods.Within the past several years, researches on InAs/InP quantum dot (QD) systems have become more and more intense in many research groups: most researchers have been attracted to investigate the QD structures, targeting at 1.55 µm emission wavelength, which has important applications in ultra-low-loss optical fibre communications [1][2][3][4][5]. On the other hand, it is expected to extend the emission wavelength of InAs/InP QDs into the mid-infrared (mid-IR) region (2-5 µm) by inserting InGaAs as the confinement layers for InAs QDs [6][7][8][9]. Extending the emission wavelength of InAs/InP QDs to mid-IR range has recently also attracted more and more researchers' attention because mid-IR optoelectronic devices are very important in a variety of military, biomedical, environmental and industrial applications, including range-finding, laser surgery and remote trace-gas sensing [10][11][12][13].…”