Publications

Shank, Joshua S.; Ames, Arlo L.; Casias, Lilian K.; Hagopian, Kaylin H.

Abstract not provided.

Casias, Lilian K.; Olesberg, Jonathon T.; Kadlec, Clark N.; Goldflam, Michael G.; Webster, Preston T.; Klem, John F.; Shaner, Eric A.

Abstract not provided.

Applied Physics Letters

Casias, Lilian K.; Morath, Christian P.; Steenbergen, Elizabeth H.; Umana-Membreno, Gilberto A.; Webster, Preston T.; Logan, Julie V.; Kim, Jin K.; Balakrishnan, Ganesh; Faraone, Lorenzo; Krishna, Sanjay

Anisotropic carrier transport properties of unintentionally doped InAs/InAs0.65Sb0.35 type-II strain-balanced superlattice material are evaluated using temperature-and field-dependent magnetotransport measurements performed in the vertical direction on a substrate-removed metal-semiconductor-metal device structure. To best isolate the measured transport to the superlattice, device fabrication entails flip-chip bonding and backside device processing to remove the substrate material and deposit contact metal directly to the bottom of an etched mesa. High-resolution mobility spectrum analysis is used to calculate the conductance contribution and corrected mixed vertical-lateral mobility of the two carrier species present. Combining the latter with lateral mobility results from in-plane magnetotransport measurements on identical superlattice material allows for the calculation of the true vertical majority electron and minority hole mobilities; amplitudes of 4.7 × 10 3 cm2/V s and 1.60 cm2/V s are determined at 77 K, respectively. The temperature-dependent results show that vertical hole mobility rapidly decreases with decreasing temperature due to trap-induced localization and then hopping transport, whereas vertical electron mobility appears phonon scattering-limited at high temperature, giving way to interface roughness scattering at low temperatures, analogous to the lateral electron mobility but with a lower overall magnitude.

Materials Advances

Logan, Julie L.; Frantz, Elias B.; Casias, Lilian K.; Short, Michael P.; Morath, Christian P.; Webster, Preston T.

As the potential applications of GaN and Ga₂O₃ are limited by the inadequacy of conventional doping techniques, specifically when uniform selective area p-type doping is required, the potential for transmutation doping of these materials is analyzed. All transmuted element concentrations are reported as a function of time for several common proton and neutron radiation sources, showing that previously published results considered a small subset of the dopants produced. A 40 MeV proton accelerator is identified as the most effective transmutation doping source considered, with a 2.25 × 10¹⁷ protons per cm² fluence yielding net concentrations of uncompensated p-type dopants of 7.7 × 10¹⁵ and 8.1 × 1015 cm^-3 for GaN and Ga₂O₃, respectively. Furthermore, it is shown that high energy proton accelerator spectra are capable of producing dopants required for magnetic and neutron detection applications, although not of the concentrations required for current applications using available irradiation methods.