Bulk unipolar diodes are majorityhyphen;carrier threehyphen;layer (nhyphen;phyphen;n) semiconductor diodes in which the current flows due to the thermionic emission of majority carriers over a barrier formed in the bulk of the material. Expressions for the barrier height of two typical bulk unipolar diodes, namely a bulk barrier diode (n++p+n) and aphyphen;plane barrier diode (n+p++n), are derived. The functional dependence of the barrier height on various technological parameters is discussed. The two diodes are quite similar in their structure and characteristics. However, thephyphen;plane barrier diode is more suitable as a majorityhyphen;carrier diode. The variation of ideality factor and the saturation current of these diodes is shown to be very similar to the metal semiconductor diode.
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