Provided is a high ruggedness HBT, including a first emitter cap layer and a second emitter cap layer formed between an emitter layer and an ohmic contact layer, or only an emitter cap layer is formed between them. When the first and second emitter cap layers are provided, bandgaps of the first or second emitter cap layer are changed, and the ruggedness of the HBT is improved. When an emitter cap layer is provided, an electron affinity of at least a portion of the emitter cap layer is less than or approximately equal to an electron affinity of the emitter layer, and the ruggedness of the HBT is improved.