| dc.description.abstract | The thesis mainly focuses on the use of aluminum gallium nitride/gallium nitride heterostructures grown on gallium nitride substrates to make vertical Schottky diodes, in order to improve the high on-voltage (VON) and high leakage current of conventional Schottky diodes . In this experiment, p-type gallium nitride was added to form a pn depletion region, achieving a normally-off operation and reducing leakage current. Then by anode etching, the etching depth exceeds the 2DEG interface to reduce the turn on voltage, and the anode is designed to be T-shaped to relax the anode edge electric field and increase the breakdown voltage. First of all, Silvaco TCAD was used to simulate the electrical properties of schottky barrier diodes without anode recess and with anode recess on the different epitaxial layers, and then discuss the characteristics of the process results.
Measure the capacitance-voltage curve at room temperature to analyze the concentration of the drift layer, as well as the forward and reverse current-voltage characteristics. The turn on voltage of the aluminum gallium nitride/gallium nitride schottky diode without anode etching is 4.05 V, when the anode etching depth exceeds the 2DEG interface, the turn on voltage reaches the lowest 0.68 V, and the minimum on-resistance is 32 mΩ·cm2, the breakdown voltage is 400 V, and the figure of merit is calculated to be 5.0 MW/cm2. Device A is added to the design of the field plate, and its designed extension length is 5 to 10 µm. The field plate extends the diode with a length of 10 µm, and the breakdown voltage is increased to 720 V.
Furthermore, use variable temperature to explore the characteristics analysis of the forward bias and reverse bias of the aluminum gallium nitride/gallium nitride schottky diode. Under the forward bias, the Schottky inhomogeneous barrier model is used to calculate the schottky barrier eliminates the uneven junction of Schottky contact after metal deposition, and then uses the reverse bias characteristic curve to further discuss the leakage current mechanism. | en_US |