Towards the ideal diode: Half-metal spin-gapless semiconductor junctions based on 2D materials

Conventional semiconductor diodes have a junction barrier that electrons have to overcome and
thus they have a threshold voltage V_T , which must be supplied to the diode to turn it on. Using the
half-metallic magnets (HMMs) and spin-gapless semiconductors (SGSs) we propose a new diode
concept, which does not have a junction barrier and whose operation principle relies on unique
spin-dependent transport properties of the HMM and SGS materials. We show that HMM and SGS
materials form an Ohmic contact under any finite forward bias, while for the reverse bias current
is blocked. Thus, the HMM-SGS junctions act as a diode with zero threshold voltage V_T, linear
current-voltage (I-V) characteristics as well as very high on/off ratio. We employ the nonequilibrium
Greens function method combined with density functional theory to demonstrate the linear I-V
characteristics of the proposed diode based on 2D spin-gapless semiconducting VS₂ and half metallic
Fe/MoS₂ planar heterojunctions. Moreover, a reconfigurable magnetic tunnel diode [1] is also realized
by vertically stacking the VS₂ and Fe/MoS₂ monolayers. [1] E. Sasioglu, S. Blügel, and I. Mertig, ACS Appl.
Electron. Mater. 1, 15521559 (2019).