High resistivity annealed low-temperature GaAs with 100 fs lifetimes

Abstract

We demonstrate the critical effect of postgrowth annealing temperature on the properties of low-temperature-grown GaAs. By using annealing temperatures substantially below the 500–600 °C commonly reported, GaAs with high resistivity and with carrier lifetimes as short as 100 fs can be routinely obtained. We discuss the optimum, but different, anneal conditions required for terahertz photoconductive emitters and detectors, and illustrate their use in a continuous-wave system.

Intense ultrashort terahertz pulses: generation and applications

“…By annealing the material, arsenic clusters are formed [31]which act as efficient traps for photo-induced carriers. Carrier lifetimes shorter than 500 fs can be achieved with this method [32][33][34]Similarly short carrier lifetimes can also be achieved with erbium nano islands embedded in GaAs [35]. Generally, there is a trade-off between optimally short carrier lifetimes and increased parasitic dark current leading to premature breakdown of the material.…”

Semiconductors for terahertz photonics applications

“…9 shows the results of three different pump-and-probe measurements performed on a sample grown at 250 o C and annealed at 650 o C. These data were obtained using femtosecond Ti:sapphire laser based experimental set-ups; all three transients show the characteristic decay time of~500 fs that can be interpreted as the electron trapping time. The electron trapping time ranges between 0.2 ps and 1 ps in the annealed LTG GaAs layers; it can be controlled by changing As and Ga beam equivalent pressure ratio [66], the growth and anneal temperatures [67,68], or by additionally doping the layer with acceptor impurity Be during the MBE growth [69].…”

Optimization and temperature dependence characteristics of low temperature In0.3Ga0.7As and In0.53Ga0.47As-In0.52Al0.48As semiconductor terahertz photoconductors

“…7,8 Furthermore, the post growth annealing of these materials results in further re-arrangement of the point defects leading to improvement of the aforementioned properties due to the subsequent formation of As precipitates. 9 The post growth annealing effect and the direct observation of As precipitation phenomenon in photoconductor materials based on LT-GaAs, relaxed LT-In 0.3 Ga 0.7 As and LT-In 0.53 Ga 0.47 As-In 0.52 Al 0.48 As multi quantum wells (MQWs) for operation at the excitation wavelengths of 800 nm, 1 μm and 1.55 μm respectively, have been demonstrated in previous works. 1,10 Although several studies have been devoted in the past years to the characterisation of such materials and their potential to be used as terahertz sources, very few reports describe the temperature dependence of the transport properties of a ioannis.kostakis@postgrad.manchester.ac.uk LT-In 0.53 Ga 0.47 As-In 0.52 Al 0.48 As and LT-In 0.3 Ga 0.7 As.…”