Parasitic bipolar effects in submicrometer GaAs MESFET's

Abstract

We report the observation for the first time of parasitic bipolar action in GaAs MESFET's. It manifests itself in the form of increased transconductance at higher drain voltage, abrupt change in output conductance (kink effect) around 4-V drain-source voltage, and a gate-voltage-dependent substrate current. These effects are explained by electron-hole pair generation in the high-field region at the drain. The holes generated are injected into the substrate where they form the base region of a parasitic lateral bipolar transistor. The effect also explains a new breakdown mechanism for short-channel enhancement-mode MES-FET's.

Pulsed measurements and circuit modeling of a new breakdown mechanism of MESFETs and HEMTs

“…This current at its tum increases the number of charge camers flowing into the impact-ionization region near the drain, thus inducing a positive feedback which reduces the drain-to-source breakdown voltage significantly. This mechanism is similar to that reported by van Zeghbroeck [20]. The feedback is very effective close to pinch-off, where high electric fields are present and impactionization is very strong, which explains the snap-back and the steep increase in Id.…”

Degradation of AlGaN/GaN high-electron mobility transistors in the current-controlled off-state breakdown

“…Gate current I G is also shown, which is by about two orders of magnitude lower than I D . Earlier reports on GaAs-based HEMT off-state breakdown 8 or GaN-based HEMT on-state breakdown 9 with S-shaped characteristics were explained by a presence of a parasitic 10 and by the current filamentation in a non-linear state of the system. 11 However, in our case, shape of I G curves after V BG is stochastic rather than Sshaped.…”

Etude des effets parasites affectant le fonctionnement des transistors à effet de champ à gaz d'électrons bidimensionnel

“…Dans les MESFETs nous avions montré que l'effet de coude était lié au comportement du substrat semi-isolant ce qui pouvait être confirmé expérimentalement par la mesure du courant de substrat [6]. La figure 2c [6,7]. Dans le cas présent, le coefficient en température, positif, de VDS (Fig.…”