A new phenomenon of highly localized, nanoscale oxidation of silicon-containing layers has been observed. The localized oxidation enhancement observed in both Si and Si(3)N(4) layers appears to be catalyzed by the migration of Ge quantum dots (QDs). The sizes, morphology, and distribution of the Ge QDs are influenced by the oxidation of the Si-bearing layers. A two-step mechanism of dissolution of Si within the Ge QDs prior to oxidation is proposed.

We report a unique approach for the inclusion of size-tunable (7-50 nm), spherical Ge quantum dots (QDs) into gate stacks of metal-oxide-semiconductor (MOS) diodes, through selective oxidation of SiGe layers over the buffer layer of Si3N4 deposited over the Si substrate. In this complementary MOS (CMOS)-compatible approach, we successfully realized high performance nm scale Ge-QD MOS photodetectors with high figures of merit of low dark current density (1.5 × 10(-3) mA cm(-2)), superior photo-current-to-dark current ratio (13 500), high photoresponsivity (2.2 A W(-1)), and fast response time (5 ns), which are ready for direct integration with Si CMOS electronic circuits. Most importantly, the detection wavelength of the Ge QDs is tunable from near infrared to near ultraviolet by reducing the QD size from 50 to 7 nm as well as the optimal photoresponsivity is tailored by the Ge QD size and the effective thickness of gate dielectrics.

This study demonstrates the precise placement of Ge quantum dots (QDs) in an SiO2 or Si3N4 matrix in a self-organized manner by thermally oxidizing SiGe in nanostructures. The effectiveness of this method is shown by a variety of geometries including nanotrenches, nanorods and polygonal nanocavities. Modulating the structural geometry and peripheral spacer materials effectively places a single Ge QD in the center of an oxidized SiGe nanostructure or individual QDs at the corners (edges). This study also reports the fabrication of Ge QD single-electron devices that exhibit clear Coulomb staircases and differential conductance oscillations at room temperature.

The influence of SiO2 and Si3N4 dielectric matrices on the structural, phonon, luminescence and thermal properties of Ge quantum dots (QDs) has been experimentally investigated. Compared with the case of QDs in SiO2 layers, Si3N4 matrix imposes large interfacial surface energy on QDs and enhances their Ostwald ripening rate, appearing to be conducive for an improvement in crystallinity and a morphology change to a more perfectly spherical shape of Ge QDs. Quantum confinement induced electronic structure modulation for Ge QDs is observed to be strongly influenced not only by the QD size but also by the embedded matrix. Both matrix and surface effects offer additional mechanisms to QD itself for controlling the optical and thermal properties of the QDs.

Recent developments in the design and fabrication of semiconductor quantum dots (QDs) have allowed access to wideranging applications in computing, 1,2 photovoltaics, 3,4 photonics, 5,6 and energy harvesting and conversion. 7,8 For these applications to be optimally realized, an unprecedentedly high degree of control over the placement, shape, density or number, and size of QDs is required. 9,10 Detailed knowledge and a detailed understanding of how the QDs are created and especially their interactions with the local environment are therefore essential to achieving this high level of control on an otherwise random growth process. To date, QDs have been created largely using "self-assembly" techniques, i.e., through random, nonlithographically controlled nucleation and growth. 11,12 A large ensemble of randomly distributed QDs is acceptable for the fabrication of QD laser and nanocrystal memory devices, but not appropriate for creating novel single-QD devices such as single-photon sources or single-electron devices. These devices