Abstract
Abstract. In this paper are considers the effect of the microrelief, dislocation structure and other defects of the epitaxial layers of the source and drain regions of the nitride HEMT transistors on the parameters of the formed ohmic contacts. The studies were carried out directly on high−power microwave transistors made of GaN/AlGaN/GaN/SiC heterostructures. Ohmic burning contacts were formed using the compositions Ti—Al—Mo—Au and Ti—Al—Ni—Au. To estimation the structural features of the contact areas, the surface microrelief at the interface of the burned contact/AlGaN and the defects formed on its surface was studied. It is shown that the resistance of the source and drain regions is largely determined by the surface microstructure at the boundary. Experimentally shown is the formation of a conducting layer in AlGaN under the ohmic contacts. The possibility of the formation of a new type of structural defects with a high aspect ratio in the contact and active areas of the devices during the formation of ohmic burned contacts is demonstrated. It is shown that the appearance of high densities of such defects leads to an increase of the device leakage currents.
Highlights
Low−contact−resistance non−gold Ta/Si/Ti/Al/Ni/Ta ohmic contacts on undoped AlGaN/GaN high−electron−mobility transistors grown on silicon // Appl
In this paper are considers the effect of the microrelief, dislocation structure and other defects of the epitaxial layers of the source and drain regions of the nitride HEMT transistors on the parameters of the formed ohmic contacts
The studies were carried out directly on high−power microwave transistors made of GaN/AlGaN/GaN/SiC heterostructures
Summary
Рассмотрено влияние микрорельефа, дислокационной структуры и других дефектов эпитаксиальных слоев в областях истока и стока нитридных транзисторов с высокой подвижностью электронов (НЕМТ) на параметры формируемых омических контактов. При формирования омических контактов на гетероструктурах AlGaN/GaN чаще всего используют металлические композиции на основе Ti/Al, подвергнутые кратковременной термической обработке. Цель работы — исследование влияния микрорельефа, дислокационной структуры и других дефектов в эпитаксиальных слоях областей истока и стока нитридных НЕМТ на параметры формируемых омических контактов. В работе [13] в области омических контактов после отжига при Т = 850 °С обнаружена фаза оксида титана Ti2O3. Экспериментально показано, что повышенная плотность дислокаций позволяет снизить температуру отжига для формирования качественных контактов до температуры 500 °С, а дальнейшее повышение температуры уже не приводит к снижению сопротивления контактных областей.
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