Research activities on surface activated bonding (SAB) of dissimilar semiconductor materials for targeting advanced energy-harvesting and energy-saving devices are reviewed.The structural and electrical properties of interfaces fabricated using the SAB technologies are examined.The change in the interface characteristics due to annealing after bonding is highlighted.The characteristics of SAB-based hybrid multi-junction solar cells, SiC/Si junctions as prototypes of wide bandgap/narrow bandgap hetero structures, and single-crystal diamond/Si junctions for integrating diamond and Si devices in the future are discussed.
Kelvin-probe force microscopy (KPFM) is a surface potential mapping technique based on dynamic-mode atomic force microscopy (AFM).It is useful to visualize carrier injection barriers and trapped charges in operating organic thin-ˆlm transistors (OTFTs).Since it is desirable to perform KPFM experiments in vacuum conditions, frequency modulation (FM) technique is often used to operate AFM/KPFM.We review two operating modes of KPFM using FM-AFM in vacuum and demonstrate visualization of the carrier injection barriers and trapped charges in OTFTs.We also introduce a method to visualize the transient distribution of the trapped charges being evacuated from the channel of the operating OTFT.
Oxide-semiconductor based gas sensors have been intensively investigated in order to improve the sensitivity and selectivity of a certain gas. This article reviews the recent research progress of gas sensors having oxide semiconductor as an active layer, in particular detecting for H2 and volatile organic compounds. The semiconductor material for gas sensors reported in this article includes SnO2, WO3, ZnO, In2O3, and NiO. The sensitivity of gas sensors having diŠerent structures and semiconductors is compared.
