Low Interface Trapped Charge Density for AlO/β-GaO (001) Metal-Insulator-Semiconductor Capacitor

Abstract

In this letter, high-performance Al2O3/β-Ga2O3 (001) metal-insulator-semiconductor (MIS) capacitor has been demonstrated. The capacitance-voltage (C-V) curves of the Al2O3/β-Ga2O3 (001) MIS capacitor remain stable under different measurement frequencies. The leakage current density is lower than 2.0 × 10 -8 A/cm 2 when the gate voltage is in the range of -5~13 V. The fixed charge and trapped charge densities in Al2O3 film are 4.4 × 10 12 and 6.0 × 10 11 cm -2 , respectively. Average and minimum interface trapped charge density (Dit) for Al2O3/β-Ga2O3 (001) interface has been extracted to be as low as 3.3 × 10 11 and 2.3 × 10 11 cm -2 eV -1 via the Terman method, respectively. The low Dit is probably attributed to the modification of vacancy defects and the introduction of hydroxyl groups at the Al2O3/β-Ga2O3 (001) interface after piranha solution pretreatment for β-Ga2O3.

Impact of NaOH solution surface treatment on Al2O3/β-Ga2O3 MOS capacitors

“…for fabricating high-performance MOSFETs. As a new semiconductor, it have been explored various dielectric materials for β-Ga 2 O 3 -based metal-oxide semiconductor capacitors (MOSCAPs), such as Al 2 O 3 [15][16][17][18][19][20][21][22], HfO 2 [23,24], SiO 2 [19,25,26], AlSiO [27,28]. Among these investigated materials, atomic layer deposited (ALD) Al 2 O 3 has been widely used due to its mature process of layer by layer deposition, large conduction band offset with β-Ga 2 O 3 (∼1.5-2.2 eV) [19] and high relative permittivity (8)(9)(10)(11) [29][30][31].…”

“…By using a combination of piranha solution cleaning, HF etching and post-deposition annealing in a FG ambient to reduce D it , a nearly hysteresis-free MOSCAP device was successfully achieved. Zhang et al [22] used piranha pretreatment to fabricate high-performance Al 2 O 3 /(001) β-Ga 2 O 3 MOSCAPs with low D it , fixed charge and trapped charge densities. At present, acid solution has been widely used to treat the β-Ga 2 O 3 surface before depositing ALD-Al 2 O 3 .…”