Hot electron transport and impact ionization in the narrow energy gap InAs1−xNx alloy

Abstract

Band structure engineering of superlattice-based short-, mid-, and long-wavelength infrared avalanche photodiodes for improved impact ionization ratesWe report an experimental study of hot electron dynamics in the narrow band gap dilute nitride alloy, InAs 1−x N x , with x up to 0.6%. The sharp increase in the conductivity of n-type InAs 1−x N x at applied electric fields above 1 kV/cm demonstrates that impact ionization dominates the hot electron dynamics. This observation, combined with the reduction in the band gap energy by the N-atoms, suggest prospects for the use of this narrow gap alloy in infrared avalanche photodiodes.

Linear magnetoresistance due to multiple-electron scattering by low-mobility islands in an inhomogeneous conductor

“…The macroscopic (>0.1 μm) inhomogeneities observed by transmission electron microscopy of our samples15 are likely to induce variations in the electronic properties. We model the effect of such inhomogenities on the electron dynamics by Monte Carlo simulations16.…”

“…At B z =0 T, the J ( E x ) curve is approximately linear at low bias. The ohmic behaviour is then followed by a slight sublinear bias dependence and, at larger electric fields, by a sharp rise of the current that is characteristic of systems switching from a state of low to high conductivity due to impact ionization and avalanche breakdown1518. At all values of E x , the magnetic field acts to suppress the current and to shift the threshold electric field for impact ionization to significantly higher values.…”

Peculiarities of the hydrogenated In(AsN) alloy

“…However, the large lattice mismatch (7.2%) [29] between the In(AsN) epilayer and the GaAs substrate, as well as a tendency for N to segregate, lead to the formation of carrier traps and recombination centers ─mainly extensive interface defects and dislocations─ that strongly reduce the material photoluminescence (PL) efficiency. [24,30] In spite of the interest in the optimization of the In(AsN) optical properties, the knowledge of the effects hydrogen has on the electronic properties of this semiconductor is still poor, with scattered experimental results. Room temperature PL efficiency increases by an order-ofmagnitude in InAs/GaAs quantum dots when irradiated in-situ with atomic hydrogen during the growth, while post-growth irradiation with molecular hydrogen has a detrimental effect on PL.…”

Impact ionization and large room-temperature magnetoresistance in micron-sized high-mobility InAs channels

“…The Ohmic behavior is then followed by a sublinear bias dependence and, at larger biases, by a sharp rise of the current and an S-shaped I-V dependence, which is characteristic of systems switching from a state of low to high conductivity due to an increase in the impact ionization rate [13]. Figure 1(b) shows the time dependence of the applied bias, V A , and the voltages, V R and V , across the resistor and device, respectively.…”

“…In a strong applied electric field, E, carriers can gain enough kinetic energy to ionize dopant impurities at low temperature [9][10][11] and/or to generate electron-hole pairs by interband impact ionization leading to avalanche breakdown [5,12,13], which greatly increases the conductivity. A magnetic field, B, applied perpendicular to the direction of the current flow, can strongly affect these impact ionization processes by increasing the binding energy of electrons bound onto impurities and hence the activation energy and electric field required for impurity ionization [9][10][11]; also, the Lorentz force exerted on the conduction electrons deflects the electron motion away from the direction of the electric field, effectively increasing the electric field required for excitation of electrons across the band gap.…”