Pre-breakdown current fluctuations and RTS noise in reverse-bias-stressed AlGaN/GaN HEMTs

In this contribution we investigate in time domain pre-breakdown current fluctuations during the device degradation between Vcrit ( 48 -50V for -2V/2min step-stress) and the breakdown voltage (Vbd 48 80V), as well as post-stress random telegraph signal (RTS) noise in Al0.24Ga0.76N(25nm)/GaN(40nm UID + 3\u3bcm C-doped)/SiC HEMTs from FBH

Random Telegraph Noise And Bursts In Reverse-Bias-Stressed AlGaN/Gan HEMTs

Random telegraph noise (RTN) and pre-breakdown bursts in gate current are studied in time domain in degraded AlGaN/GaN HEMTs subjected to reverse bias stress. Analysis of RTN under both forward and reverse gate bias indicates that the origin of RTN is due to modulation of current via a stress-induced percolation path by a trap. At voltages close to the device breakdown voltage, large amplitude pre-breakdown bursts have been observed. Their origin is discussed in terms of dielectric wear out of passivation layer at the gate edge

Reconstructive procedures for disturbed functions within the upper airway: pharyngeal breathing/snoring

Breathing disorders which have their origin within the pharynx mainly occur during sleep. These so-called obstructive sleep-related breathing disorders include three different disturbances which have to be distinguished properly: simple snoring, upper airway resistance syndrome (UARS) and obstructive sleep apnea (OSA). Each disturbance requires a different treatment.Simple snoring does not affect the physical health of the snorer himself, but often leads to social problems due to the annoying character of the breathing sounds. Appropriate treatment modalities are oral devices and transcutaneous or ttransmucosal electrical stimulation of the muscles of the floor of the mouth via surface electrodes. As reconstructive surgical procedures adenotomies, tonsillectomies, tonsillotomies, or adenotonsillectomies are successfully used in children. Moreover, in adults radiofrequency treatments of the tonsils, the soft palate and of the base of tongue, as well as uvulopalatopharyngoplasty (UPPP), laser-assisted uvulopalatoplasty (LAUP) and palatal implants are adequate treatments for simple snoring.Adequate therapies for UARS and mild OSA (less than 20 breathing events per hour of sleep) are oral appliances. Nasal continuos positive airway pressure (NCPAP) ventilation is a very successful treatment modality, but shows low compliance in these patients, as daytime symptoms like excessive sleepiness or or impaired cognitive functions are often unincisive in patients with mild OSA. Reconstructive procedures like UPPP, radiofrequency surgery of the tonsils or the base of tongue, hyoid suspension, mandibular osteotomy with genioglossus advancement (MO) are successful treatment options either as isolated procedures or in combination within so-called multi-level surgery concepts.Goldstandard for the treatment of moderate to severe OSA is the nCPAP ventilation. All patients should at least try this treatment modality. Only in the rare cases of nCPAP failure (2%) and in the relatively frequent cases of nCPAP incompliance (30%) reconstructive surgical procedures become necessary as second choice treatments. These are adenectomies, tonsillectomies, tonsillotomies in children and hyoid suspension, MO, multi-level surgery concepts, or maxillomandibular advancement osteotomies in adults

Explanation of threshold voltage scaling in enhancement-mode InAlN/AlN-GaN metal oxide semiconductor high electron mobility transistors on Si substrates

We present enhancement-mode GaN high electron mobility transistors on Si substrates with ZrO2 gate dielectrics of thicknesses t(ox) between 10 and 24 nm. The oxide interlayers between the InAlN/AlN barrier and gate metal allow raising the device threshold voltage up to + 2.3 V and reduce gate leakage current to less than 100 nA/mm with a high drain current on/off ratio of 4 orders of magnitude. We use a model that explains the observed linear dependence of the threshold voltage on tox and allows determining fixed charges at the oxide/barrier interface. (C) 2012 Elsevier B. V. All rights reserved