Current instabilities in GaN-based devices

Nonalloyed ohmic contacts in AlGaN/GaN HEMTs by ion implantation with reduced activation annealing temperature

“…The maximum drain current I max of the implanted sample was 1.15 A/mm at V G = +1 V, and the pinchoff voltage V p was −4.4 V. Fig. 3 shows that the 200-ns current values are lower than the dc values, indicating a limited amount of RFdc dispersion [12]. The control sample showed similar current performance, a similar amount of dispersion, I max = 1 A/mm, and V p = −5.5 V. The reduction of I max and V p can be attributed to sample inhomogeneity, although further investigation is necessary.…”

Testing the Temperature Limits of GaN-Based HEMT Devices

“…Passivation and the properties of the dielectric/ semiconductor interface, which may be considered an amorphous/crystalline heterojunction, are therefore rather critical. High lateral electrical fields may lead to lateral charge injection, compensating the surface donor in the gate/drain high field drift region and giving rise to the virtual gate effect [5], [6]. Furthermore, the growth of the GaN buffer layer commences usually on a highly disordered nucleation layer on substrates reaching from silicon carbide (SiC) and sapphire to (111) oriented silicon (Si).…”

Quantitative observation and discrimination of AlGaN- and GaN-related deep levels in AlGaN∕GaN heterostructures using capacitance deep level optical spectroscopy

“…Power amplifiers based on AlGaN / GaN heterojunction field effect transistors ͑HFETs͒ are hampered by defects attributed to the AlGaN surface [1][2][3] and the GaN buffer [4][5][6] that exert detrimental influence upon device performance. Thus, quantitative observation of band gap states in AlGaN / GaN heterostructures provides an important metric for optimizing material growth and minimizing the impact of defects.…”