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We study the potential and feasibility of high hole mobility transistors (HHMTs) based on flexible AlGaInN/GaN heterostructures using numerical simulation. We develop a map for the sheet density of two-dimensional hole gas (2DHG) at different mole fractions of AlN, GaN, and InN of AlGaInN with mechanical bending conditions. External compressive strain via bending can induce relatively high density of 2DHG (e.g., > 8\times 10^12 cm ^-2 ) while keeping InN fraction low (<0.3) so that 2DHG channel can be formed in a GaN layer. We show the electronic energy band diagrams, family curves of I-V characteristics, and transfer characteristics of an In0.25 Al0.75N/GaN heterostructure in different bending conditions. By bending up, 2DHG is formed to perform the device function as HHMTs. Without bending, 2-D electron gas is induced and the devices function as high electron mobility transistors. This unique property can be used in complementary integrated circuits for high-power and high-temperature applications. [ABSTRACT FROM AUTHOR]

We theoretically study the change of the performance characteristics with various mechanical bending conditions for flexible thin-film transistors (TFTs) by two-dimensional device simulation. The characteristics of newly developed flexible TFTs with high crystalline quality and high carrier mobility are more sensitive to the degree of bending. We developed a model to estimate the change in the characteristics as a function of curvature radius of the channel with a focus on scattering of carriers in a bent TFT. Field-effect mobility decreases by bending, e.g., ~11% with a radius at R\,\,=30 mm and a knee voltage increases, while a threshold voltage remains the same. This model can be extended to other flexible TFTs with bending. [ABSTRACT FROM PUBLISHER]

Demonstrated are visible GaN-based light-emitting diodes (LEDs) on economical large-area Si substrates using an advanced device and packaging architecture to improve optical output power, while reducing manufacturing costs. The process employs thin-film-flip-chip devices and wafer-level chip-scale packages and uses through-Si-via substrate and anisotropic conductive film for bonding. The improved curvature control region is applied in the epitaxial growth of the LED structure on a Si substrate to achieve flat wafers for epitaxial structures at room temperature, which is critical for wafer-level bonding. External quantum efficiency and light-output power at 350 mA increase by $\sim 12$ % compared with those of conventional flip-chip LEDs grown on a sapphire substrate. The devices also show a reverse-bias leakage current failure rate of <10%. [ABSTRACT FROM PUBLISHER]

We demonstrate flip-chip light-emitting diodes (FC-LEDs) on a flexible yttria-stabilized zirconia (YSZ) substrate and compare them with FC-LEDs on a polymeric substrate. Degradation of luminescence intensity and red-shift of peak wavelength are not observed for the LED on the flexible YSZ, unlike one on the polyimide substrate, due to improved capability to remove the generated heat from the chip to the substrate. Thermal distribution measurements and finite-element simulations show improved thermal management by the flexible ceramic as compared with previously developed flexible LEDs on polymeric substrates. The results present an improved solution to high power operation of flexible LEDs. [ABSTRACT FROM PUBLISHER]