Increased reliability of AlGaN/GaN HEMTs versus temperature using deuterium
Résumé
Low frequency noise (LFN) is a reliable diagnostic tool to evaluate and locate the defects of a technology. In this study, LFN is used to assess effects of deuterium (H + ions) in diffusion condition on the robustness of 0.25 *2*75 µm² gate area AlGaN/GaN high electron mobility transistors (HEMT) grown on Si substrate. H + Ions are diffused from the above AlGaN/GaN layer through the AlGaN/GaN interface and GaN layer, notably under the gated channel where the defects are located. Two batches of devices are stressed under high temperature condition at 400°C during 5 minutes (step 1) and 500°C during 15 minutes (step 2). The first batch is composed with 8 deuterated transistors while the second batch is composed with 8 non deuterated transistors. Static measurements and low frequency noise spectral density measurements of the drain current (S ID) are examined after each step of temperature. The first step does not reveal any degradation, while the second step highlights significative differences between the deuterated and non deuterated devices: LFN of deuterated devices remains constant, whereas LFN of non deuterated devices increases (GR superimposed with 1/f flicker noise). The deuteration of the devices can open the way to robust temperature devices, as AlGaN/GaN HEMT are dedicated to applications at high power and high temperature. I. INTRODUCTION The development of wideband gap technology is convenient for integrated circuits design such as VCO and LNA. AlGaN/GaN high electron mobility transistors stand as promising candidates to substitute GaAs and SiGe technologies for power applications at high frequency. They take advantages from a higher breakdown voltage, higher power density and higher thermal conductivity that are suitable for power applications while keeping good carrier mobility for high frequency applications. Recent studies revealed also very good low noise performances for this technology [1] [2]. Thus, GaN devices can pretend to be used in transceivers for power amplification, for low noise amplification and for frequency synthesis (voltage controlled oscillation) over a wideband of frequencies ranging from L up to Ka band. LFN measurements provide valuable information about noise source location and failure prediction [3], and can also assess devices robustness. In a previous work, deuterium has been used as a probe in diffusion condition to locate the
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