Surface states on n-type Al0.24Ga0.76As characterized by deep-level transient spectroscopy

Abstract

Articles you may be interested inSurface states on n-type Al 0.24 Ga 0.76 As were studied using capacitance deep-level transient spectroscopy ͑DLTS͒. Two types of hole-like traps ͑labeled as H1 and H2 in this work͒ were observed in a Al 0.24 Ga 0.76 As/In 0.22 Ga 0.78 As pseudomorphic high-electron-mobility transistor with a multifinger gate. But, no hole-like traps were observed in the fat field-effect transistor ͑FATFET͒ having a negligible ratio of the ungated surface to the total area between the source and the drain. This provides evidence that the hole-like trap peaks in the DLTS spectra originated from surface states at the ungated Al 0.24 Ga 0.76 As regions exposed between gate and source/drain electrodes. The activation energies for both surface states were determined to be 0.50Ϯ0.03 and 0.81Ϯ0.01 eV. The comparison of activation energies of the two surface states with the Schottky barrier height 0.66Ϯ0.01 eV suggests that H1 and H2 are deeply related to the Fermi energy pinning levels at the Al 0.24 Ga 0.76 As surface.

Characterisation of the effect of surface passivation with SiO2/SiN on deep levels in AlGaN/GaN/Si HEMTs

“…Similar going DLTS signal after passivation, have been studied for AlGaAs/GaAs HEMTs since 1986 [16e18].In these cases; there is good evidence that GaAs or AlGaAs surface states are the origin of those traps. That is, these states can trap injected electrons from the gate during the filling pulse (virtual gate), and produce a capacitance transient and a DLTS signal [18,19]. So, to eliminate the surface states in both GaAs and GaN, various passivation processes have been developed.…”

Traps in AlGaN∕GaN∕SiC heterostructures studied by deep level transient spectroscopy

“…Negatively going DLTS signals or hole-like traps ͑if negative valleys appear͒ have been studied for GaAs metalsemiconductor field-effect transistors and AlGaAs/ GaAs HEMTs since 1986. [11][12][13] In these cases, there is good evidence that GaAs or AlGaAs surface states are the origin of the hole-like traps. That is, these states can trap injected electrons from the gate during the filling pulse, and produce a positive capacitance transient, 13 which simulates a hole trap.…”

“…[11][12][13] In these cases, there is good evidence that GaAs or AlGaAs surface states are the origin of the hole-like traps. That is, these states can trap injected electrons from the gate during the filling pulse, and produce a positive capacitance transient, 13 which simulates a hole trap. To eliminate the surface states, in both GaAs and GaN, various passivation processes have been developed.…”

Defect states in red-emittingInxAl1−xAsquantum dots

“…25 Hole traps in AlGaAs devices have been reported in n-type AlGaAs/InGaAs PHEMT's which were attributed to surface states at ungated AlGaAs regions, but their reported activation energies were much higher than the E a ϭ0.37 eV measured in this work. 26 DLTS analysis in the InAlAs/n-AlGaAs structures presents an even more complex picture. The multiple peak structure found at longer filling pulse times is similar to what other studies have found for DX-like centers in GaAs/ AlGaAs superlattices.…”

“…As was reported in earlier studies, 11,12,29 interfacial defects have been known to give strong DLTS signals and are also known to hamper radiative recombination from QD states. Interfacial defects have been observed 25,26 to have a rapid increase in signal intensity with applied bias as the bias sweeps over the interfacial region. An unambiguous identification of the origin of this broad low-temperature peak that is seen mainly for short filling pulses in InAlAs/n-AlGaAs QD's can only be made if the defect concentration can be reduced to a much lower density that the QD volumetric density, which will require additional growth optimization in future work.…”