Comparative study of donor-induced quantum dots in Si nano-channels by single-electron transport characterization and Kelvin probe force microscopy

Abstract

We comparatively study donor-induced quantum dots in Si nanoscale-channel transistors for a wide range of doping concentration by analysis of single-electron tunneling transport and surface potential measured by Kelvin probe force microscopy (KPFM). By correlating KPFM observations of donor-induced potential landscapes with simulations based on Thomas-Fermi approximation, it is demonstrated that single-electron tunneling transport at lowest gate voltages (for smallest coverage of screening electrons) is governed most frequently by only one dominant quantum dot, regardless of doping concentration. Doping concentration, however, primarily affects the internal structure of the quantum dot. At low concentrations, individual donors form most of the quantum dots, i.e., “donor-atom” quantum dots. In contrast, at high concentrations above metal-insulator transition, closely placed donors instead of individual donors form more complex quantum dots, i.e., “donor-cluster” quantum dots. The potential depth of these “donor-cluster” quantum dots is significantly reduced by increasing gate voltage (increasing coverage of screening electrons), leading to the occurrence of multiple competing quantum dots.

Specific features of defect formation in the n­Si <P> single crystals at electron irradiation

“…The most convenient and the most affordable semiconductor to form planar structures, which are the base of modern integrated electronics, is silicon, due to its unique properties, almost unlimited natural stocks, commercial availability, and cultivation technology [6][7][8][9]. Silicon is the base for constructing and improving super-large and ultra-fast integrated circuits, new elements for micro-and nanoelectronics of our time [6,[9][10][11][12]. silicon is the model semiconductor because electronic paramagnetic resonance (EPR) provided for the possibility to determine the atomic configuration and electron structure of radiation defects [13].…”

Tunneling in Systems of Coupled Dopant-Atoms in Silicon Nano-devices

“…Furthermore, as marked in the lower zoom-in panel for negative V BG , it is possible to identify fine modulations of the potential inside the heavily-doped slit. These features can be ascribed to “clusters” of several P-donors grouped together inside the selectively-doped region, according to our detailed analysis correlated with dopant-induced potential simulations [ 25 ]. It is found that such clusters (containing even more than 10 P-donors) can work as dominant QDs in the tunneling transport characteristics, with a significant effect of the selective-doping technique in controlling the QD position within the channel [ 26 ].…”

“…6b , suggest that there is a certain correlation between the number of P-donors coupled together and the energy spectrum of the silicon nanostructures. Further evidence has been obtained from the analysis of KPFM measurements correlated with simulations of dopant-induced potential landscapes [ 25 , 26 ]. Typical I D - V G characteristics for devices of this type are shown in Fig.…”

“…It is important to note that such molecular-like systems, with a rich energy spectrum and tunability of their properties, can also work as fundamental units for dopant-based devices, but they are significantly different than the case of individual, atomic P-donors. With further optimization of the selective-doping technique and additional understanding of inter-dopant coupling physics [ 25 , 26 ] at the fundamental level and in extremely scaled-down structures, it can be expected that these systems can offer another pathway toward achieving high-temperature tunneling operation of dopant-based devices.…”

Dopant-Based Charge Sensing Utilizing P-I-N Nanojunction

“…5a. In fact, these donors, due to the superposition of electronic potentials, create a cluster [22]. In such a cluster, an ionized boron (B − state) acceptor raises a local electronic potential, limiting the flowing current.…”