High quality dielectric‐semiconductor interfaces are critical for reliable high‐performance transistors. This paper reports the in situ metal–organic chemical vapor deposition of Al2O3on β‐Ga2O3as a potentially better alternative to the most commonly used atomic layer deposition (ALD). The growth of Al2O3is performed in the same reactor as Ga2O3using trimethylaluminum and O2as precursors without breaking the vacuum at a growth temperature of 600 °C. The fast and slow near interface traps at the Al2O3/β‐Ga2O3interface are identified and quantified using stressed capacitance–voltage (CV) measurements on metal oxide semiconductor capacitor (MOSCAP) structures. The density of shallow and deep level initially filled traps (Dit) are measured using ultraviolet‐assisted CV technique. The average Ditfor the MOSCAP is determined to be 6.4
- Award ID(s):
- 2154535
- NSF-PAR ID:
- 10420588
- Date Published:
- Journal Name:
- Journal of Vacuum Science & Technology A
- Volume:
- 41
- Issue:
- 2
- ISSN:
- 0734-2101
- Page Range / eLocation ID:
- 023203
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract × 1011cm−2eV−1. The conduction band offset of the Al2O3/ Ga2O3interface is also determined from CV measurements and found out to be 1.7 eV which is in close agreement with the existing literature reports of ALD Al2O3/Ga2O3interface. The current–voltage characteristics are also analyzed and the average breakdown field is extracted to be approximately 5.8 MV cm−1. This in situ Al2O3dielectric on β‐Ga2O3with improved dielectric properties can enable Ga2O3‐based high‐performance devices. -
Focused Ga + ion milling of lightly Si-doped, n-type Ga 2 O 3 was performed with 2–30 kV ions at normal incidence and beam currents that were a function of beam voltage, 65 nA for 30 kV, 26 nA for 10 kV, 13 nA for 5 kV, and 7.1 nA for 2 kV, to keep the milling depth constant at 100 nm. Approximate milling rates were 15, 6, 2.75, and 1.5 μm 3 /s for 30, 10, 5, and 2 kV, respectively. The electrical effects of the ion damage were characterized by Schottky barrier height and diode ideality factor on vertical rectifier structures comprising 10 μm epitaxial n-Ga 2 O 3 on n + Ga 2 O 3 substrates, while the structural damage was imaged by transmission electron microscopy. The reverse bias leakage was largely unaffected even by milling at 30 kV beam energy, while the forward current-voltage characteristics showed significant deterioration at 5 kV, with an increase in the ideality factor from 1.25 to 2.25. The I–V characteristics no longer showed rectification for the 30 kV condition. Subsequent annealing up to 400 °C produced substantial recovery of the I–V characteristics for all beam energies and was sufficient to restore the initial ideality factor completely for beam energies up to 5 kV. Even the 30 kV-exposed rectifiers showed a recovery of the ideality factor to 1.8. The surface morphology of the ion-milled Ga 2 O 3 was smooth even at 30 kV ion energy, with no evidence for preferential sputtering of the oxygen. The surface region was not amorphized by extended ion milling (35 min) at 5 kV with the samples held at 25 °C, as determined by electron diffraction patterns, and significant recovery of the lattice order was observed after annealing at 400 °C.more » « less
-
more » « less
Abstract Wafer bonding of
β ‐Ga2O3and N‐polar GaN single crystal substrates is demonstrated by adding ZnO as a “glue” interlayer. The wafers are fully bonded such that Newton rings are not observed. Temperature‐dependent current‐voltage (I –V ) measurements are conducted on the as‐bonded Ga2O3/ZnO/N‐polar GaN test structure and after annealing at 600 °C and 1100 °C. The impact of post‐annealing temperature on the electrical and structural characteristics of the bonded samples is investigated. A consistently ohmic‐like characteristic is obtained by annealing the bonded wafers at 1100 °C in N2,which is in part due to crystallization of ZnO and diffusion of Ga into ZnO which makes it n‐type doped. The wafer bonding ofβ ‐Ga2O3and GaN achieved in this work is promising to combine the material merits of both GaN and Ga2O3targeting breakthrough high‐frequency and high‐power device performances. -
We present a review of the published experimental and simulation radiation damage results in Ga 2 O 3 . All of the polytypes of Ga 2 O 3 are expected to show similar radiation resistance as GaN and SiC, considering their average bond strengths. However, this is not enough to explain the orders of magnitude difference of the relative resistance to radiation damage of these materials compared to GaAs and dynamic annealing of defects is much more effective in Ga 2 O 3 . It is important to examine the effect of all types of radiation, given that Ga 2 O 3 devices will potentially be deployed both in space and terrestrial applications. Octahedral gallium monovacancies are the main defects produced under most radiation conditions because of the larger cross-section for interaction compared to oxygen vacancies. Proton irradiation introduces two main paramagnetic defects in Ga 2 O 3 , which are stable at room temperature. Charge carrier removal can be explained by Fermi-level pinning far from the conduction band minimum due to gallium interstitials (Ga i ), vacancies (V Ga ), and antisites (Ga O ). One of the most important parameters to establish is the carrier removal rate for each type of radiation, since this directly impacts the current in devices such as transistors or rectifiers. When compared to the displacement damage predicted by the Stopping and Range of Ions in Matter(SRIM) code, the carrier removal rates are generally much lower and take into account the electrical nature of the defects created. With few experimental or simulation studies on single event effects (SEE) in Ga 2 O 3 , it is apparent that while other wide bandgap semiconductors like SiC and GaN are robust against displacement damage and total ionizing dose, they display significant vulnerability to single event effects at high Linear Energy Transfer (LET) and at much lower biases than expected. We have analyzed the transient response of β -Ga 2 O 3 rectifiers to heavy-ion strikes via TCAD simulations. Using field metal rings improves the breakdown voltage and biasing those rings can help control the breakdown voltage. Such biased rings help in the removal of the charge deposited by the ion strike.more » « less
-
more » « less
β -Ga2O3is an emerging material and has the potential to revolutionize power electronics due to its ultra-wide-bandgap (UWBG) and lower native substrate cost compared to Silicon Carbide and Gallium Nitride. Sinceβ -Ga2O3technology is still not mature, experimental study ofβ -Ga2O3is difficult and expensive. Technology-Computer-Aided Design (TCAD) is thus a cost-effective way to study the potentials and limitations ofβ -Ga2O3devices. In this paper, TCAD parameters calibrated to experiments are presented. They are used to perform the simulations in heterojunction p-NiO/n-Ga2O3diode, Schottky diode, and normally-off Ga2O3vertical FinFET. Besides the current-voltage (I-V) simulations, breakdown, capacitance-voltage (C-V), and short-circuit ruggedness simulations with robust setups are discussed. TCAD Sentaurus is used in the simulations but the methodologies can be applied in other simulators easily. This paves the road to performing a holistic study ofβ -Ga2O3devices using TCAD.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1116/6.0002264
