Passivation effects in Ni∕AlGaN∕GaN Schottky diodes by annealing

Abstract

The Ni∕AlGaN interfaces in AlGaN∕GaN Schottky diodes were investigated to explore the physical origin of postannealing effects in AlGaN∕GaN heterostructures using electron beam induced current (EBIC) and current-voltage characteristics. Black spot density in EBIC images of as-deposited Ni∕AlGaN∕GaN diodes is in the same order of 108cm−2 as the dislocation density of AlGaN∕GaN heterostructures characterized by atomic force microscopy, indicating that recombination sites near Ni∕AlGaN interface are related to dislocations. The EBIC images of the annealed diodes showed that the postannealing reduced the electrically active states at the Schottky metal/AlGaN interfaces. The thermal reaction near Ni∕AlGaN interface due to the postannealing induced passivation effect, leading to decrease in reverse leakage current density, ideality factor, and saturation current density of the diodes and increase in the Schottky barrier height. We suggest that the postannealing process is an effective way to passivate the AlGaN∕GaN heterojunction field effect transistors.

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

“…Reliability, performance and life time combination of these devices are much higher than other devices. However, in order to improve the performance of these devices; the effects of surface passivation, dielectric layer (Al 2 O 3 , Si 3 N 4 ) insertion, surface treatments with chemical or plasma have been investigated [11][12][13][14][15][16][17][18][19]. However, it still difficult to obtain a high quality GaN epilayer because of the large lattice mismatch and large difference in the thermal expansion coefficients between the GaN film, sapphire, and SiC substrate.…”

On the profile of frequency and voltage dependent interface states and series resistance in (Ni/Au)/Al0.22Ga0.78N/AlN/GaN heterostructures by using current–voltage (I–V) and admittance spectroscopy methods

“…They have been intensively studied as candidates for highpower devices, as well as for high-speed and high-temperature operations [1][2][3][4][5][6][7][8]. Controlling interface states (N ss ) and series resistance (R s ) is an important issue in these structures for high power, high speed and high temperature applications [4]. In order to improve the performance of these devices the effect of surface passivation, dielectric layer (Al 2 O 3 , Si 3 N 4 ) insertion, surface treatments with chemical or plasma have been investigated [4][5][6][7][8].…”

“…Controlling interface states (N ss ) and series resistance (R s ) is an important issue in these structures for high power, high speed and high temperature applications [4]. In order to improve the performance of these devices the effect of surface passivation, dielectric layer (Al 2 O 3 , Si 3 N 4 ) insertion, surface treatments with chemical or plasma have been investigated [4][5][6][7][8]. Nevertheless satisfactory understanding in all details such as the frequency dependence of N ss and R s as function of applied bias voltage has still not been achieved.…”

“…They have been intensively studied as candidates for highpower devices, as well as for high-speed and high-temperature operations [1][2][3][4][5][6][7][8]. Controlling interface states (N ss ) and series resistance (R s ) is an important issue in these structures for high power, high speed and high temperature applications [4].…”

“…More than three decades; AlGaN/AlN/GaN high electron mobility transistors (HEMT) have attracted much attention due to their promising applications in microwave and optoelectronic devices [1][2][3][4][5][6][7][8]. They have been intensively studied as candidates for highpower devices, as well as for high-speed and high-temperature operations [1][2][3][4][5][6][7][8].…”