High quality HfO2/p-GaSb(001) metal-oxide-semiconductor capacitors with 0.8 nm equivalent oxide thickness

Abstract

We investigate in-situ cleaning of GaSb surfaces and its effect on the electrical performance of p-type GaSb metal-oxide-semiconductor capacitor (MOSCAP) using a remote hydrogen plasma. Ultrathin HfO 2 films grown by atomic layer deposition were used as a high permittivity gate dielectric. Compared to conventional ex-situ chemical cleaning methods, the in-situ GaSb surface treatment resulted in a drastic improvement in the impedance characteristics of the MOSCAPs, directly evidencing a much lower interface trap density and enhanced Fermi level movement efficiency. We demonstrate that by using a combination of ex-situ and in-situ surface cleaning steps, aggressively scaled HfO 2 /p-GaSb MOSCAP structures with a low equivalent oxide thickness of 0.8 nm and efficient gate modulation of the surface potential are achieved, allowing to push the Fermi level far away from the valence band edge high up into the band gap of GaSb.

Oxidation of GaSb(100) and its control studied by scanning tunneling microscopy and spectroscopy

“…2 Gallium antimonide (GaSb) has attracted an increasing interest as for the channel material of future MOS transistors, in particular, due to a superior mobility of holes in GaSb. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] The GaSb oxidation at the insulator interfaces such as atomiclayer-deposited (ALD) Al 2 O 3 /GaSb and HfO 2 /GaSb has been found to cause various oxidation states of GaSb including Ga 2 O, Ga 2 O 3 , Sb 2 O 3 , and/or Sb 2 O 5 according to x-ray photoelectron spectroscopy (XPS) measurements. 10,18 By obtaining interrelationship between the interfacial chemistry from, for example, XPS measurements and capacitance-voltage (C-V) characterization of the same interfaces, the effects of the oxidation states on the electrical properties of the interfaces have been clarified: it is interesting that neither Ga 2 O 3 -nor Sb 2 O 3type interface phase is necessarily harmful to the electrical performance.…”

Эволюция физико-химических свойств поверхности GaSb(100) в растворах сульфида аммония

“…Отжиг поверхности в сверхвысоком вакууме не позволяет удалить этот оксидный слой без потери стехиометрии кристалла [10,11]. В этой связи были предложены различные методы обработки водородной [12] и азотной плазмой [13]. Химическая обработка раствором HCl с последующей промывкой изопропиловым спиртом позволяет уменьшить толщину оксидного слоя на поверхности GaSb(100) [10].…”

<italic>In Situ</italic> Process Control of Trilayer Gate-Stacks on p-Germanium With 0.85-nm EOT

“…1(a)], including (i) in-situ plasma clean to prepare atomically flat and pristine Ge surface, (ii) in-situ passivation with GeO x to form a low D it interface, (iii) Al 2 O 3 ALD deposition to stabilize the interface, and (iv) high-k HfO 2 ALD deposition to suppress leakage current. This approach is not limited to Ge but may be also applicable to other semiconductors forming thermodynamically unstable but passivation-friendly interfaces with high-k dielectrics, such as compound semiconductors [7].…”