Dissociation of indirect excitons: discontinuity and bistability in the tunnel current of 2D electron-hole layers

Bistability and discontinuity in the tunnel current of two-dimensional electron-hole layers

“…In other words, the hysteresis could be described as a first-order phase transition. 2 In addition, we notice that the magnetic field behavior of the width of the bistability ͑Fig. 12͒ bears a strong resemblance to the behavior of the critical temperature for the excitonic state predicted in Refs.…”

“…2͑b͒. 1,2 We denote the states corresponding to the upper and lower branch of the bistability the ''high-current state'' ͑HCS͒ and ''low-current state'' ͑LCS͒, respectively.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In these systems, the e-h recombination time can be made as long as 1 sec, therefore allowing thermalization of the carriers to the lattice temperature, a situation that is never reached in strictly 2D e-h systems because of the higher recombination rate. With respect to real atoms, 21 indirect excitons are particularly attractive because of their light mass, which is expected to allow condensation at T ϳ1 K, rather than in the K regime.…”

“…To date, most of the experimental work has been done on the optical properties of undoped double quantum wells ͑DQW's͒, [4][5][6][14][15][16] which provide a natural tool for obtaining charge separation. As already realized by Kuramoto and Horie, 17 another attractive possibility is to study the transport 1,2,20 and optical 3 properties of p-i-n single-barrier heterostructures ͑SBH's͒, in which 2D e-h layers of equal density accumulate under forward bias at opposite sides of the barrier. With respect to DQW's, p-i-n SBH's have several advantages.…”

“…1͒. [1][2][3] In such a device, two limits are known. At low densities (nϳ10 10 cm Ϫ2 ), Neves et al 20 have observed resonant tunneling via indirect exciton states, which manifests itself as peaks in the low-temperature (TՇ10 K) I(V) curves.…”