Fundamentals and practice of metal contacts to wide band gap semiconductor devices

Abstract

Presented are the theoretical and experimental fundamentals of the fabrication of ohmic contacts to n‐ and p‐type wide band gap semiconductors such as SiC and GaN. In particular, the Ni‐Si/n‐SiC, Al‐Ti/p‐SiC, Ti‐Al/n‐GaN and Ni‐Au/p‐GaN systems are discussed with the focus on the thermally activated chemical reactions taking place at the metal‐semiconductor interface, that lead to the appearance of ohmic behaviour in the contact. Examples of reactions at very intimate interfaces are shown, which are irresolvable using even such sophisticated characterisation methods as high‐resolution transmission electron microscopy and can only be explained using modelling. The issue of thermal stability of the contacts is discussed and the introduction of specifically designed diffusion barriers (eg. Ta‐Si‐N) into the contact metallisation stack is presented as a solution improving drastically the thermal stability of the contacts without degrading their electrical properties. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural origin of the different glass-forming abilities in ZrCu and ZrNi metallic glasses

“…The front electrode on the p-type layer was formed by aluminum (Al)-titanium (Ti) alloy annealed at 1000°C and a nickel (Ni)-chromium (Cr) contact was formed on the back of the n-type SiC substrate by annealing at 650-750°C. 9 Rapid thermal annealing was performed in argon atmosphere. Values of the specific contact resistance were determined by linear Transmission Line Method.…”

“…8 The development of stable ohmic contacts to SiC has been subject of extensive research. [9][10][11] Also, hardness against ionizing and particle radiation has been studied in detail. [12][13][14][15][16] Robustness against UV irradiation is an important issue for UV dose control systems in germicidal and bactericidal UV applications.…”

Nanoflower ZnO thin-film grown by hydrothermal technique based Schottky diode

“…Based on the fundamental Schottky rule, when a metal and semiconductor contact is formed, the rectifying or ohmic behavior of the junction is determined by the metal work function and the semiconductor electron affinity [2] . Bulk and thin-film Schottky diodes have been well reported [3] . However, high-performing wide bandgap material thin-film Schottky diodes might be a challenge [1,3,4] .…”

“…Bulk and thin-film Schottky diodes have been well reported [3] . However, high-performing wide bandgap material thin-film Schottky diodes might be a challenge [1,3,4] . One wide bandgap material that attracts great interest for thin-film Schottky diodes is ZnO.…”

Investigation of Electrical and Interfacial Properties of Improved Ohmic Contact on p-Type GaN

“…Therefore, in order to further block the inter-diffusion of metal layers, the quality the metal layers should be improved. 25 On the other hand, a thin amorphous layer is formed on the GaN surface immediately by exposing to the air after MOCVD growth or chemical cleaning, including about 2 nm of Ga 2 O 3 and adsorbed carbon or oxide contaminations, analyzed by XPS. 26,27 The electrical measurements results show that the contamination layer on the p-GaN z E-mail: adingsun2014@sinano.ac.cn; fsli2015@sinano.ac.cn surface act as a barrier for carrier transport through the interface.…”