<i>In Situ </i>Microfabrication and Measurements of Bi₂Se₃Ultrathin Films in a Multichamber System with a Focused Ion Beam, Molecular Beam Epitaxy, and Four-Tip Scanning Tunneling Microscope

Abstract

Ultrathin films of Bi2Se3 grown on Si(111) substrate were etched into submicron-width wires by using a focused ion beam (FIB), and their electrical resistance was measured using the four-probe method with a four-tip scanning tunneling microscope. All of the procedures were performed in situ in ultrahigh vacuum without exposing the sample to air. One-dimensional conduction of the films was confirmed from the dependence of the resistance on the length of wire under measurement, meaning that successful lossless current path control laterally as well as vertically can be obtained with FIB etching. Protecting the sample surface from unintentional gallium ion beam irradiation in the FIB process was also found to be important for maintaining the intrinsic electrical properties of the Bi2Se3 films.

Materials analysis and focused ion beam nanofabrication of topological insulator Bi2Se3

“…Directly growing nanotstructures bottom-up into the necessary geometries and defect densities would be ideal, but controlled growth and scaling of such devices is complicated. An alternative is to use top-down methods, such as ion milling, to modify the Bi 2 Se 3 [16][17][18][19][20][21][22][23][24][25] .…”

“…1. FIB milling utilizes Ga + ions to sputter away a target material and can be used to both sculpt the material 16,17,21,22 and introduce defects 18,21 . Recent transport studies have shown that FIB-created nanowires of Bi 2 Se 3 exhibit increased photoconductivity at room temperature 22 and retain signatures of their topological surface states at low temperature 16,17 .…”

Charge and spin transport on surfaces and atomic layers measured by multi-probe techniques

“…This opens up an interesting expectation for ultralow energy-consumption devices by using spin current. Figure 14(b) is an example of such a device, fabricated by focussed ion beam in UHV combined with four-tip STM system [56]. The electric current I is made flow through leads at the center and the volt age V is measured between leads apart from the current leads by distance L; the spin current is expected to flow along the horizontal strip of a topologocal insultor.…”

Progress and development in multiple-probe scanning probe microscopes

“…Iwata 等人 [82] 和Bolopion等人 [83] 分别开发了具有实时触觉 反馈的纳米镊子系统, 他们采用不同的偏转检测方 法, Iwata等人利用自检测探针, 而Bolopion等人采用 的是激光反射法. [59] , ZnO [60] QP-STM Bi 2 Se 3 [61] , CoSi 2 [43,62] 二维 DP-STM Au表面 [63] , 3-octylthiophene薄膜 [64,65] , 石墨烯 [66,67] DP-AFM α-sexithiophene [44] , 并五苯薄膜 [68] QP-STM 石墨烯 [69,70] , Si(111)4×1-In [71] , Bi 2 Te 2 Se表面 [72,73] , Pentacene薄膜 [74,75] , Au表面 [76] , Te/Si(111)-(1×1)界面 [77] 评 述 图 6 DP-AFM并行成像与操作 [33] . (a) 并行成像与操作纳米颗粒的示意图.…”