ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Electroluminescence spectroscopy of short gate high-electron-mobility transistors (HEMTs) on InP substrates is performed at cryogenic temperatures. Electroluminescence is a reliable tool to investigate impact ionization as compared to studies based on gate current which depend on the weakness of the intrinsic gate current intensity. In on-state biased devices, a low energy (0.7–0.9 eV) recombination band is observed which is related to radiative recombination of carriers created by impact ionization in the low band gap InGaAs channel. The evolution of the luminescence intensity versus bias applied to the device shows that the electroluminescence intensity and impact ionization depend on two competing parameters: the electric field in the gate–drain access area and the drain current intensity. We show that the so-called "kink'' effect, which is a noticeable increase of the output conductance and which is observed at relatively moderate drain bias (600–750 mV) in our devices, is not correlated with impact ionization. The electroluminescence of the device in the off state is also investigated. This study allows the direct observation of impact ionization in the off-biased channel of InP-based HEMTs. In this low current regime, the electroluminescence intensity follows the electric field, i.e., the drain–gate voltage until breakdown of the device occurs. The voltage breakdown of the device in the off state is discussed in terms of impact ionization in the InGaAs channel due to hot carriers originating from the gate leakage current. Finally, a method for reducing or avoiding impact ionization in these devices, i.e., for increasing the device reliability, is discussed. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.362749
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