Ultrafast 1.55-μm photoresponses in low-temperature-grown InGaAs/InAlAs quantum wells

Abstract

Doping with Be was found to be very effective for shortening of carrier lifetime in InGaAs/InAlAs multiple quantum wells (MQWs) grown at low temperature by molecular beam epitaxy. The MQW materials have carrier lifetimes controllable from a few tens of picoseconds to 1 ps in the 1.55-μm wavelength region, coupled with a large optical nonlinearity due to an excitonic feature, implying applicability to ultrafast optical devices in the fiber-optic communication. The carrier lifetime was measured by a time-resolved pump-probe method using an optical source based on a 1.535-μm semiconductor laser. We also investigated the resistivity, carrier density, and Hall mobility in the MQWs.

Electrical properties and ultrafast photo-response of InGaAs/InP grown by low-temperature molecular beam epitaxy with a GaAs decomposition source

“…The carrier lifetime of the samples decreased to 1.86 ps as the doping concentration increased to 1 Â 10 19 cm À3 . This tendency is in agreement with Takahashi et al [1]. The shortening of carrier lifetime in the samples grown at 250 C may result from Be acceptors, and excess arsenic donors, that act as the recombination center where electrons and holes are trapped.…”

“…Conventional semiconductor materials have long recombination carrier lifetimes in the ns range, making them difficult to be used for ultrafast optical devices. Recently, to overcome this slow photoresponse, techniques for low-temperature-grown (LTG) semiconductor materials have emerged for practical reasons [1]. While LTG GaAs has been extensively studied, the potential of making devices with an ultrafast photo-response in the 1.55 mm wavelength region has sparked interest in LTG InGaAs and InGaAs/InAlAs quantum well structures, particularly those lattice matched to InP substrates [2,3].…”

Low-temperature growth and post-growth annealing of GaAsSb

“…Especially the LT growth of InGaAs and AlInAs has been under investigation, motivated either by the use in connection with optical fiber systems operating at 1.3 [11] and 1.55 mm [12,13] or by the use as an insulating layer [14,15].…”

Terahertz detectors from Be-doped low-temperature grown InGaAs/InAlAs: Interplay of annealing and terahertz performance

“…First, we notice that the electron lifetime decreases for higher Be doping concentrations since Be dopants ionize additional antisite defects, which in turn increases the density of fast trapping centers. 28,29,31 Furthermore, the fact that Be dopants ionize additional antisites explains why the conductivity of all the samples shown in Fig. 2 was electron-like, although the Be doping concentration was up to two orders of magnitude higher than the residual electron concentration of the undoped material.…”

“…27 Apart from the pure compensatory effect of Be-doping, the electron lifetime in LTG-InGaAs decreases for a higher Be-doping concentration due to the ionization of additional As Ga defects by Be dopants. 28,29 Electron lifetimes below 0.5 ps were measured in LTG-InGaAs:Be. However, carrier concentrations below 1 × 10 14 cm -3 could only be obtained by an additional annealing step in combination with the growth of a multilayer heterostructure consisting of Be-doped InGaAs and Be-doped InAlAs.…”