A vertical semiconductor device in which pinch-off characteristics and breakdown voltage characteristics can be stably improved by fixing the electric potential of a p-type GaN barrier layer with certainty is provided. The micro-converter is at least substantially block-shaped and includes an at least substantially rectangular acoustic membrane tensioned therein transversely of a longitudinal direction. The internal format has a number of exponent bits and a number of fraction bits sufficient to support each of the floating point architectures.