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In this work, the structural and electrical properties of metalorganic chemical vapor deposited Si-doped β-(AlxGa1−x)2O3 thin films grown on (010) β-Ga2O3 substrates are investigated as a function of Al composition. The room temperature Hall mobility of 101 cm2/V s and low temperature peak mobility (T = 65 K) of 1157 cm2/V s at carrier concentrations of 6.56 × 1017 and 2.30 × 1017 cm−3 are measured from 6% Al composition samples, respectively. The quantitative secondary ion mass spectroscopy (SIMS) characterization reveals a strong dependence of Si and other unintentional impurities, such as C, H, and Cl concentrations in β-(AlxGa1−x)2O3 thin films, with different Al compositions. Higher Al compositions in β-(AlxGa1−x)2O3 result in lower net carrier concentrations due to the reduction of Si incorporation efficiency and the increase of C and H impurity levels that act as compensating acceptors in β-(AlxGa1−x)2O3 films. Lowering the growth chamber pressure reduces Si concentrations in β-(AlxGa1−x)2O3 films due to the increase of Al compositions as evidenced by comprehensive SIMS and Hall characterizations. Due to the increase of lattice mismatch between the epifilm and substrate, higher Al compositions lead to cracking in β-(AlxGa1−x)2O3 films grown on β-Ga2O3 substrates. The (100) cleavage plane is identified as a major cracking plane limiting the growth of high-quality Si-doped (010) β-(AlxGa1−x)2O3 films beyond the critical thicknesses, which leads to highly anisotropic and inhomogeneous behaviors in terms of conductivity. [ABSTRACT FROM AUTHOR]

The lack of p-type doping has impeded the development of vertical gallium oxide (Ga2O3) devices. Current blocking layers (CBLs) using implanted deep acceptors have been used to demonstrate vertical devices. This paper presents a pioneering demonstration of in situ Mg-doped β-Ga2O3 CBLs grown using metal–organic chemical vapor deposition. The Mg-doping density during growth was calibrated by quantitative secondary ion mass spectroscopy. Electrical test structures were designed with in situ Mg doped layers with various targeted Mg doping concentrations. The effectiveness of the CBL is characterized by using temperature-dependent current–voltage measurements using n-Mg-doped-n structures, providing crucial insight into the underlying mechanisms. Pulsed measurements show similar blocking characteristics as DC. To further validate the experimental results, a TCAD simulation is performed, and the electrically active effective doping is found to be dependent on the Mg-doping density, offering an alternate perspective on the optimization of CBL performance. Breakdown measurements show a peak 4 MV/cm field strength. [ABSTRACT FROM AUTHOR]

In this Letter, the role of background carbon in metalorganic chemical vapor deposition (MOCVD) β-Ga2O3 growth using trimethylgallium (TMGa) as the Ga precursor was investigated. The quantitative C and H incorporations in MOCVD β-Ga2O3 thin films grown at different growth rates and temperatures were measured via quantitative secondary ion mass spectroscopy (SIMS). The SIMS results revealed both [C] and [H] increase as the TMGa molar flow rate/growth rate increases or growth temperature decreases. The intentional Si incorporation in MOCVD β-Ga2O3 thin films decreases as the growth rate increases or the growth temperature decreases. For films grown at relatively fast growth rates (GRs) (TMGa > 58 μmol/min, GR > 2.8 μm/h) or relatively low temperature (<950 °C), the [C] increases faster than that of the [H]. The experimental results from this study demonstrate the previously predicted theory—H can effectively passivate the compensation effect of C in n-type β-Ga2O3. The extracted net doping concentration from quantitative SIMS {[Si]-([C]-[H])} agrees well with the free carrier concentration measured from Hall measurement. The revealing of the role of C compensation in MOCVD β-Ga2O3 and the effect of H incorporation will provide guidance on designing material synthesis for targeted device applications. [ABSTRACT FROM AUTHOR]