Terahertz Emission from Collapsing Field Domains during Switching of a Gallium Arsenide Bipolar Transistor

Abstract

Broadband pulsed THz emission with peak power in the sub-mW range has been observed experimentally during avalanche switching in a gallium arsenide bipolar junction transistor at room temperature, while significantly higher total generated power is predicted in simulations. The emission is attributed to very fast oscillations in the conductivity current across the switching channels, which appear as a result of temporal evolution of the field domains generated in highly dense electron-hole plasma. This plasma is formed in turn by powerful impact ionization in multiple field domains of ultrahigh amplitude.

Picosecond-Range Avalanche Switching of High-Voltage Diodes: Si Versus GaAs Structures

“…The key finding that has helped to explain such anomalous dynamics is the discovery of collapsing high-field domains that spontaneously appear in electronhole plasma due to negative differential electron mobility in GaAs [19]- [21]. These domains were originally predicted as a mechanism that explains picosecond-range switching and terahertz emission in GaAs avalanche transistors [19], [20]. The mechanism that initiates the instability of the spatially uniform current flow is essentially the same as that for the well-known Gunn effect and is related to negative differential conductivity [19]- [21].…”

Переходной процесс выключения 4H-SiC биполярного транзистора из режима глубокого насыщения

“…Одномерная численная модель, использованная в дан-ной работе, неоднократно успешно использовалась для описания Si, GaAs и SiC биполярных транзисторов, в том числе и в режимах предельно больших плотностей тока [12,[17][18][19]. Детали процесса моделирования подроб-но описаны в работе [17].…”

Transmission Subterahertz Imaging Utilizing Milliwatt-Range Nanosecond Pulses from Miniature, Collapsing-Domain-Based Avalanche Source

“…This huge amplitude (up to 0.6 MV/cm) causes monstrous impact ionization in the domains and very fast growth in the density of electron-hole (e-h) plasma surrounding the domains. This results, in turn, in drastic domain shrinkage ("collapsing" [ 25 ]) with corresponding growth in the amplitude and further increase in the ionization rate. Very powerful impact generation of e-h plasma and very fast domain shrinkage cause unique superfast switching in GaAs avalanche transistors [ 26 , 27 ] and apparently in GaAs thyristors [ 28 ].…”

“…[ 25 ] peak power emitted in sub-THz range by a sample used in those fi rst experiments was around ~0.1 mW. That structure and chip design was certainly not optimized as a sub-THz source, and purpose of the experiment [ 25 ] was only a demonstration of the emission in the support of the collapsing domain concept. Here we report on first steps towards development of an optimized sub-THz (mm-wave) pulsed emitter, and demonstrate several examples of possible applications.…”

“…Very powerful impact generation of e-h plasma and very fast domain shrinkage cause unique superfast switching in GaAs avalanche transistors [ 26 , 27 ] and apparently in GaAs thyristors [ 28 ]. Even more exciting for applications is copious emission in sub-THz range [ 25 ] caused by picosecond-range current oscillations, which result from nucleation and annihilation of multiple collapsing domains and certain plasma waves. Despite the observed phenomenon that we term "collapsing fi eld domains" has similarities with Gunn effect [ 29 ], and fundamental physical reason [ 30 ] (negative differential mobility, NDM, and GaAs) is also similar, there are drastic differences between two phenomena.…”