Effects of Crystallinity on the Electrical Characteristics of Counter-Doped Polycrystalline Germanium Thin-Film Transistor via Continuous-Wave Laser Crystallization

Abstract

The crystallinity of polycrystalline germanium (poly-Ge) films were demonstrated through continuous-wave laser crystallization (CLC) with Gaussian-distribution beam profile. The different grain sizes of CLC poly-Ge were observed in their three crystallization regions, which were 2 μm, 680 nm, and 90 nm for the central, transition, and edge regions, respectively. Furthermore, the relation between crystallinity and carrier types in these three regions of counter-doped CLC poly-Ge films were investigated. In the central and transition regions, the CLC poly-Ge films with relatively low hole concentration were easily converted to n-type poly-Ge films through a counter-doping process. In contrast, the edge region with poor crystallinity exhibited p-type behavior due to high defect-generated hole concentration. According to these material properties of counter-doped CLC poly-Ge films, the corresponding transfer characteristics of p-channel poly-Ge thin-film transistor for three crystallization regions were further investigated. Subsequently, high-performance p-channel poly-Ge thin-film transistors in the central region exhibited a superior field-effect mobility of 792.2 cm 2 /V-s.INDEX TERMS Polycrystalline germanium (poly-Ge), continuous-wave laser crystallization (CLC), counter-doping (CD), thin-film transistor (TFT).

Low-temperature process design for inversion mode n-channel thin-film-transistor on polycrystalline Ge formed by solid-phase crystallization

“…5,7,8) Therefore, the more accessible operation mode for preparing an n-channel TFT on SPC-Ge is an inversion mode with rectifying S/D. However, compared with p-channel TFT 7,[9][10][11][12] and junctionless n-channel TFT research, [13][14][15] the number of reports on inversion mode n-channel TFTs on poly-Ge is limited. [16][17][18] In this study, we design a fabrication process for high-performance n-channel TFTs on SPC-Ge at low temperatures.…”

High-Performance P-Type Germanium Tri-Gate FETs via Green Nanosecond Laser Crystallization and Counter Doping for Monolithic 3-D ICs

“…In addition, for the crystallized Ge, there would be a large amount of hole concentration regenerated from the defect in the Ge films [16]. Counter doping (CD) technique is one of the simplest methods to suppress this phenomenon > REPLACE THIS LINE WITH YOUR MANUSCRIPT ID NUMBER (DOUBLE-CLICK HERE TO EDIT) < [17], [18]. However, there were few studies discussing the effect of LC and CD techniques on the Ge Tri-gate FETs with narrower channel widths for future application in monolithic 3D ICs.…”

Graded Crystalline HfO₂ Gate Dielectric Layer for High-k/Ge MOS Gate Stack

“…Most recently, back-end of line (BEOL) compatible monolithic three-dimensional (M3D) integration of high performance memory and logic has attracted much attention [6,7]. Under the constraint of thermal budget (< 400 °C), polycrystalline (p-) Ge is one of the strong candidates along with p-Si, metal-oxides, and two-dimensional semiconductors [7][8][9][10][11]. Although the scaling of Ge devices to the physical limit and thus thin equivalent oxide thickness (EOT) of gate-oxide are not aggressively demanded for BEOL-M3D integration, the thermal budget and other process conditions should be considered.…”