Employing hole-array recess of barrier layer of AlGaN/GaN Heterostructures to reduce annealing Temperature of Ohmic contact

Abstract

Ohmic contact to AlGaN/GaN heterostructures employing hole-array recess of barrier layer is conducted in this paper, in which an Ohmic contact resistance of 0.2 Ωmm with an annealing temperature of 800 °C with 15 nm deep holes recessed on the AlGaN layer before annealing is obtained. The annealing temperature and metal morphology post annealing is compared between Ohmic contacts with and without hole array recess. The annealing temperature required for the Ohmic contact with hole recess to achieve minimum ohmic contact resistance is 40 °C lower when compared to an ordinary Ohmic contact without hole array recess. Additionally metal morphology is significantly improved, such as the reduction of irregular metal particles and metal bumps forming in the annealing process, smaller alloying grains, perfectly straight metal edge and no educts existing at metal sidewalls are realized. The results demonstrated in this paper are beneficial to the performance, yield and reliability of relevant devices and circuits.

Analysis of the Influence of a Number of Design and Technological Factors on the Parameters of Power Algan/Gan/Sic Hemt

“…Образование островковых агломератов отмечалось практически во всех работах, посвящённых анализу металлических контактов нитридных гетеростуктур. Основой агломератов, как правило, являются островки Ni-Al [25], которые обычно окружены золотом, вернее, Au-Al; это образование видно на микрофотографиях в виде светлого кольца (рис. 15).…”

Improvement of AlGaN/GaN High-Electron-Mobility Transistor Radio Frequency Performance Using Ohmic Etching Patterns for Ka-Band Applications

“…Solutions have been proposed to reduce the parasitic influences of GaN-based HEMTs through barrier layer recessing, ohmic regrowth, and n-type doping to lower the source and drain resistances ( R s and R d ) for direct current (DC) characteristic improvements [ 18 , 19 ]. In advance, researchers have reported simulated and experimental results regarding contact resistivity improvements using several ohmic recessing patterns to increase the current paths and device saturation current density [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Optimization of Ohmic Contact for AlGaN/GaN HEMT on Low-Resistivity Silicon

“…Ti/Al based metal schemes like Ti/Al/Ni/Au, Ti/Al/Mo/Au, Ta/Ti/Al/Ni/Au, Ti/Al/Ta/Au and Ti/Al/Ti/TiN annealed at elevated temperatures have been successfully demonstrated to reduce contact resistance [3] [4] [5] [6] [7]. Recess of the barrier layer at the drain and source has also proven to be successful [8] [9]. Regrowth of N-type GaN is so far the most effective way to reduce ohmic contact resistance, however the procedure is currently cost prohibitive and adds significant complexity to the fabrication process.…”