Growth of honeycomb-symmetrical Mn nanodots arrays on Si(111)-7 × 7 surfaces

Abstract

The growth of well-ordered Mn nanodots arrays on Si(111)-7×7 reconstructed surface was investigated by means of scanning tunneling microscopy (STM) as well as Kinetic Monte Carlo (KMC) simulation. Mn atoms deposited slowly onto elevated substrates were observed to occupy preferentially on the faulted half unit cells (FHUCs) of Si(111)-7×7 surface. The preference occupancy in the FHUCs, P F , defined as the ratio of number of FHUCs occupied by Mn nanodots to number of all occupied in two halves, decreases with increasing deposition rate as well as decreasing substrate temperature. The KMC simulations, which are in good agreement with the experimental results, were employed to optimize the growth conditions, including deposition rate and substrate temperature, for the self-organized growth of Mn nanodots arrays on Si(111)-7×7 reconstructed surface. By adjusting the deposition rate, one can control the growth of well-ordered and uniform Mn nanodots arrays to form either a triangular symmetry or a honeycomb one.

Spontaneous formation of Mn nanocluster arrays on aSi(111)−7×7surface observed with STM

“…1͒ and is higher than the reported Mn preference of 91%, optimized with a higher deposition rate. 21 This demonstrates the effect of utilizing an extremely lowdeposition rate. Meanwhile, the "bright triangle stars" that appeared in Fig.…”

“…23͒ to 0.17 ML/min. 21,22 However, neither the local structures and symmetry of Mn clusters nor the occupation sites of individual Mn atoms have been obtained. Furthermore, the reported elevated substrate temperature between 180°C to 260°C might lead to the Mn/Si reaction.…”

Measurement of Tunneling Current of Self-Assembled Viologen Derivative Molecules Using Scanning Tunneling Microscopy

“…The normal state of the probe was verified by investigating a well-arranged silicon atomic surface for a 10 Â 10 nm 2 scanning area. 6) Images of the self-assembled viologen derivatives were produced using a normal probe; then the current-voltage (I-V) and differential conductance (dI=dV{V) characteristics of viologen derivatives were measured by monitoring tunneling voltage while varying the voltage on the sample from À2:5 to þ2:5 V. According to Table I in the case of VC 8 SH, we found molecular length, width, and tilting angle values of to be 0.13 nm, 2.34 nm, and 7.3 , respectively. We found the molecular length of (VC 8 SH) to be 0.13 nm after it selfassembled onto the Au(111) substrate, whereas, the real length of a molecule of (VC 8 SH) was about 1.94 nm.…”