ترغب بنشر مسار تعليمي؟ اضغط هنا

Spinning Holes in Semiconductors

31   0   0.0 ( 0 )
 نشر من قبل Herbert A. Fertig
 تاريخ النشر 2003
  مجال البحث فيزياء
والبحث باللغة English
 تأليف H.A. Fertig




اسأل ChatGPT حول البحث

The electron spin is emerging as a new powerful tool in the electronics and optics industries. Many proposed applications involve the creation of spin currents, which so far have proven to be difficult to produce in semiconductor environments. A new theoretical analysis shows this might be achieved using holes rather than electrons in semiconductors with significant spin-orbit coupling.

قيم البحث

اقرأ أيضاً

99 - Yao Yao 2019
Different from traditional semiconductors, the organic semiconductors normally possess moderate many-body interactions with respect to charge, exciton, spin and phonons. In particular, the diagonal electron-phonon couplings give rise to the spatial l ocalization and the off-diagonal couplings refer to the delocalization. With the competition between them, the electrons are dispersive in a finite extent and unfavorable towards thermal equilibrium. In this context, the quantities from the statistical mechanics such as the entropy have to be reexamined. In order to bridge the localization-delocalization duality and the device performance in organic semiconductors, the quantum heat engine model is employed to describe the charge, exciton and spin dynamics. We adopt the adaptive time-dependent density matrix renormalization group algorithm to calculate the time evolution of the out-of-time-ordered correlator (OTOC), a quantum dynamic measurement of the entanglement entropy, in three models with two kinds of competing many-body interactions: two-bath lattice model with a single electron, Frenkel-charge transfer mixed model, and the Merrifield model for singlet fission. We respectively investigate the parameter regime that the system is in the many-body localization (MBL) phase indicated by the behavior of OTOC. It is recognized that the novel effects of coherent electron hopping, the ultrafast charge separation and the dissociation of triplet pairs are closely related to the MBL effect. Our investigation unifies the intrinsic mechanisms correlating to charge, exciton and spin into a single framework of quantum entanglement entropy, which may help clarify the complicated and diverse phenomena in organic semiconductors.
Twisted heterostructures of two-dimensional crystals offer almost unlimited scope for the design of novel metamaterials. Here we demonstrate a room-temperature ferroelectric semiconductor that is assembled using mono- or few- layer MoS2. These van de r Waals heterostructures feature broken inversion symmetry, which, together with the asymmetry of atomic arrangement at the interface of two 2D crystals, enables ferroelectric domains with alternating out-of-plane polarisation arranged into a twist-controlled network. The latter can be moved by applying out-of-plane electrical fields, as visualized in situ using channelling contrast electron microscopy. The interfacial charge transfer for the observed ferroelectric domains is quantified using Kelvin probe force microscopy and agrees well with theoretical calculations. The movement of domain walls and their bending rigidity also agrees well with our modelling results. Furthermore, we demonstrate proof-of-principle field-effect transistors, where the channel resistance exhibits a pronounced hysteresis governed by pinning of ferroelectric domain walls. Our results show a potential venue towards room temperature electronic and optoelectronic semiconductor devices with built-in ferroelectric memory functions.
Tightly bound excitons in monolayer semiconductors represent a versatile platform to study two-dimensional propagation of neutral quasiparticles. Their intrinsic properties, however, can be severely obscured by spatial energy fluctuations due to a hi gh sensitivity to the immediate environment. Here, we take advantage of the encapsulation of individual layers in hexagonal boron nitride to strongly suppress environmental disorder. Diffusion of excitons is then directly monitored using time- and spatially-resolved emission microscopy at ambient conditions. We consistently find very efficient propagation with linear diffusion coefficients up to 10,cm$^2$/s, corresponding to room temperature effective mobilities as high as 400,cm$^2$/Vs as well as a correlation between rapid diffusion and short population lifetime. At elevated densities we detect distinct signatures of many-particle interactions and consequences of strongly suppressed Auger-like exciton-exciton annihilation. A combination of analytical and numerical theoretical approaches is employed to provide pathways towards comprehensive understanding of the observed linear and non-linear propagation phenomena. We emphasize the role of dark exciton states and present a mechanism for diffusion facilitated by free electron hole plasma from entropy-ionized excitons.
We compute the transient dynamics of phonons in contact with high energy hot charge carriers in 12 polar and non-polar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in electronic te mperature departs significantly from a single-exponential model at times ranging from 1 ps to 15 ps after electronic excitation, a phenomenon concomitant with the appearance of non-thermal vibrational modes. We demonstrate that these effects result from the slow thermalization within the phonon subsystem, caused by the large heterogeneity in the timescales of electron-phonon and phonon-phonon interactions in these materials. We propose a generalized 2-temperature model accounting for the phonon thermalization as a limiting step of electron-phonon thermalization, which captures the full thermal relaxation of hot electrons and holes in semiconductors. A direct consequence of our findings is that, for semiconductors, information about the spectral distribution of electron-phonon and phonon-phonon coupling can be extracted from the multi-exponential behavior of the electronic temperature.
The monolayer transition metal dichalcogenides are an emergent semiconductor platform exhibiting rich excitonic physics with coupled spin-valley degree of freedom and optical addressability. Here, we report a new series of low energy excitonic emissi on lines in the photoluminescence spectrum of ultraclean monolayer WSe2. These excitonic satellites are composed of three major peaks with energy separations matching known phonons, and appear only with electron doping. They possess homogenous spatial and spectral distribution, strong power saturation, and anomalously long population (> 6 ${mu}$s) and polarization lifetimes (> 100 ns). Resonant excitation of the free inter- and intra-valley bright trions leads to opposite optical orientation of the satellites, while excitation of the free dark trion resonance suppresses the satellites photoluminescence. Defect-controlled crystal synthesis and scanning tunneling microscopy measurements provide corroboration that these features are dark excitons bound to dilute donors, along with associated phonon replicas. Our work opens opportunities to engineer homogenous single emitters and explore collective quantum optical phenomena using intrinsic donor-bound excitons in ultraclean 2D semiconductors.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا