1. Field
At least one example embodiment relates to nitride-based semiconductor devices, and in particular, high-power nitride-based semiconductor diodes in which nitride-based semiconductors form a heterostructure and/or integrated devices using the same.
2. Description of the Related Art
Silicon (Si) and gallium arsenide (GaAs) are used in a wide range of semiconductor devices for low-power apparatuses and (in the case of Si) low-frequency apparatuses. However, these semiconductor materials have a limitation for use in high-power and/or high-frequency devices due to their relatively small bandgaps (for example, at room temperature, 1.12 eV for Si and 1.42 eV for GaAs) and relatively low breakdown voltages.
Due to this limitation, attention on high-power, high-temperature, and/or high-frequency apparatuses and devices has shifted to a wide bandgap semiconductor material, for example, silicon carbide (for example, 2.996 eV for alpha SiC at room temperature), or Group III nitride (for example, 3.36 eV for GaN at room temperature). These materials typically have a higher electric field breakdown intensity and a higher electron saturation speed than GaAs and Si.
From among Group III-nitride semiconductor devices, for use in high-power and/or high-frequency devices, a device in which semiconductor materials having different bandgap energy levels forms a heterostructure is particularly getting attention. In such a device, a two-dimensional electron gas (2DEG) is formed on a contact surface of two semiconductors, which may provide advantages during operation in a number of events. 2DEG forms a scaling layer in a smaller bandgap material, and may have an excessively high sheet electron concentration, for example, 1013 carrier/cm2. In addition, electrons generated in a wider bandgap semiconductor material may move to the 2DEG, allowing high electron mobility due to reduced ionized impurity scattering. A combination of a high carrier concentration and a high carrier mobility provides a high-power and high-frequency device having a high performance.