A near-ideal and homogeneous β-Ga2O3 Schottky diode with Co contact for a doping level of ∼4.2 × 1017 cm−3 in the drift layer where the Boltzmann approximation is valid is reported. Unlike Si or GaN, thermionic emission is shown to be the dominant current conduction mechanism in the β-Ga2O3 Schottky diode at this doping level. A wide depletion region appended with a large built-in potential is observed to limit the thermionic field emission current, which is otherwise evident in narrower bandgap semiconductor (such as Si or GaN) Schottky diodes having a similar carrier concentration in the drift region. The results shown in this study can be used to identify the theoretical limits of drift layer doping beyond which the ideality factor and reverse leakage current should start deteriorating in ultra-wide bandgap semiconductor based Schottky diodes.

In this work, we report on a self-powered ultraviolet photodiode realized using lateral polarity structure (LPS) GaN films. The opposite nature of the polarization charge yields different barrier heights at the standard Ni/Au Schottky contact interface of N-polar and III-polar GaN films. As a result, a natural nonzero built-in potential is obtained in the LPS GaN photodiode, which showed photoresponsivity even at 0 V applied bias. The self-powered mechanism inside such an LPS GaN photodiode is discussed in detail by a combination of simulation prediction and experimental validation. Furthermore, a variation in the doping concentration of the adjacent III- and N-polar GaN domain is shown to improve the photoresponsivity compared to the conventional III-polar photodiode. Thus, this work validates that the LPS GaN photodiode is a promising candidate to realize self-powered operation and a general design rule for the photodiode with in-plane built-in potential.

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