α-Ga2O3has the corundum structure analogous to that of α-Al2O3. The bandgap energy of α-Ga2O3is 5.3 eV and is greater than that of β-Ga2O3, making the α-phase attractive for devices that benefit from its wider bandgap. The O–H and O–D centers produced by the implantation of H+and D+into α-Ga2O3have been studied by infrared spectroscopy and complementary theory. An O–H line at 3269 cm−1is assigned to H complexed with a Ga vacancy (VGa), similar to the case of H trapped by an Al vacancy (VAl) in α-Al2O3. The isolated VGaand VAldefects in α-Ga2O3and α-Al2O3are found by theory to have a “shifted” vacancy-interstitial-vacancy equilibrium configuration, similar to VGain β-Ga2O3, which also has shifted structures. However, the addition of H causes the complex with H trapped at an unshifted vacancy to have the lowest energy in both α-Ga2O3and α-Al2O3.
The ion implantation of H+and D+into Ga2O3produces several O–H and O–D centers that have been investigated by vibrational spectroscopy. These defects include the dominant VGa(1)-2H and VGa(1)-2D centers studied previously along with additional defects that can be converted into this structure by thermal annealing. The polarization dependence of the spectra has also been analyzed to determine the directions of the transition moments of the defects and to provide information about defect structure. Our experimental results show that the implantation of H+(or D+) into Ga2O3produces two classes of defects with different polarization properties. Theory finds that these O–H (or O–D) centers are based on two shifted configurations of a Ga(1) vacancy that trap H (or D) atom(s). The interaction of VGa(1)-nD centers with other defects in the implanted samples has also been investigated to help explain the number of O–D lines seen and their reactions upon annealing. Hydrogenated divacancy VGa(1)-VOcenters have been considered as an example.
more » « less- PAR ID:
- 10207370
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- ECS Journal of Solid State Science and Technology
- Volume:
- 9
- Issue:
- 12
- ISSN:
- 2162-8769
- Page Range / eLocation ID:
- Article No. 125006
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
more » « less
Abstract Organofunctionalized tetranuclear clusters [(MIICl)2(VIVO)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2)}2] (
1 , M=Co,2 : M=Zn) containing an unprecedented oxometallacyclic {M2V2Cl2N4O8} (M=Co, Zn) framework have been prepared by solvothermal reactions. The new oxo‐alkoxide compounds were fully characterized by spectroscopic methods, magnetic susceptibility measurement, DFT and ab initio computational methods, and complete single‐crystal X‐ray diffraction structure analysis. The isostructural clusters are formed of edge‐sharing octahedral {VO5N} and trigonal bipyramidal {MO3NCl} units. Diethanolamine ligates the bimetallic lacunary double cubane core of1 and2 in an unusual two‐mode fashion, unobserved previously. In the crystalline state, the clusters of1 and2 are joined by hydrogen bonds to form a three‐dimensional network structure. Magnetic susceptibility data indicate weakly antiferromagnetic interactions between the vanadium centers [J iso(VIV−VIV)=−5.4(1 ); −3.9(2 ) cm−1], and inequivalent antiferromagnetic interactions between the cobalt and vanadium centers [J iso(VIV−CoII)=−12.6 and −7.5 cm−1] contained in1 . -
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. -
more » « less
Abstract A unique field termination structure combining a three-step field plate with nitrogen ion implantation to enhance the reverse breakdown performance of Pt/
β -Ga2O3Schottky barrier diodes (SBDs) and NiO/β -Ga2O3heterojunction diodes (HJDs) is reported. The fabricated devices showed a lowR on,spof 6.2 mΩ cm2for SBDs and 6.8 mΩ cm2for HJDs. HJDs showed a 0.8 V turn-on voltage along with an ideality factor of 1.1 leading to a low effective on-resistance of 18 mΩ cm2. The devices also showed low reverse leakage current (<1 mA cm−2) and a breakdown voltage of ∼1.4 kV. These results offer an alternative, simpler route for fabricating high-performance kilovolt-classβ -Ga2O3diodes. -
more » « less
Abstract Electrospray ionization (ESI) can produce a wide range of gas‐phase uranyl (UO22+) complexes for tandem mass spectrometry studies of intrinsic structure and reactivity. We describe here the formation and collision‐induced dissociation (CID) of [UO2(NO3)3]−and [UO2(NO3)2(O2)]−. Multiple‐stage CID experiments reveal that the complexes dissociate in reactions that involve elimination of O2, NO2, or NO3, and subsequent reactions of interesting uranyl‐oxo product ions with (neutral) H2O and/or O2were investigated. Density functional theory (DFT) calculations reproduce experimental results and show that dissociation of nitrate ligands, with ejection of neutral NO2, is favored for both [UO2(NO3)3]−and [UO2(NO3)2(O2)]−. DFT calculations also suggest that H2O adducts to products such as [UO2(O)(NO3)]−spontaneously rearrange to create dihydroxides and that addition of O2is favored over addition of H2O to formally U(V) species.
