On the origin of spin loss in GaMnN/InGaN light-emitting diodes

Abstract

Spin polarization of GaMnN/InGaN light-emitting diodes grown by molecular beam epitaxy is analyzed. In spite of the ferromagnetic behavior of the GaMnN spin injector, the diodes are shown to exhibit very low efficiency of spin injection. Based on resonant optical orientation spectroscopy, the spin loss in the structures is shown to be largely due to fast spin relaxation within the InGaN spin detector, which itself destroys any spin polarization generated by optical spin orientation or electrical spin injection.

Effect of Si Co Doping on Ferromagnetic Properties of GaGdN

“…Recent interest has focused on GaN as a base for DMSs due to its wide band gap, robust nature, and well-established manufacturing base for lightemitting diodes and laser diodes. Transition metal dopants in GaN have been extensively studied, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] but the rare earth elements have lately gained momentum as a dopant for dilute magnetic semiconductor applications. [21][22][23] There is potential for incorporating this type of material into applications such as spin valves, magnetic tunnel junctions, and spin LEDs.…”

Ferromagnetism in Transition-Metal Doped ZnO

“…Spin relaxation within the spin sublevels of the ground state seems to be within the range that is detectable, based on past results from InGaN. [87][88][89] Viewing from the observed 50 ps spin relaxation time for the exciton ground state in InGaN QW, a spin LED or a device that uses ZnO-based materials for spin transport has to operate on a similar or shorter time scale to be effective even with an RTD type of spin injection. For example, a pulsed operation mode should be employed.…”

“…This energy dependence is opposite to what we observed in the InGaN quantum wells. [87][88][89] If one can design a resonant tunneling diode (RTD) such that the polarized spins carried by either electrons or holes can be injected directly to the ground state of the corresponding carriers in a spin detector without involving energy and momentum relaxation, there may be a hope of preserving the spin polarization much better. Spin relaxation within the spin sublevels of the ground state seems to be within the range that is detectable, based on past results from InGaN.…”

“…This list includes exchange-biased samples, spindependent resonant tunneling diodes, magnetic tunnel junctions, and spin-polarized light-emitting diodes (spin LEDs). [87][88][89][90][91][92][93][94][95][96][97][98] The presence of tunable wavefunction overlap between magnetic ions and carriers confined to quantum structures has also been reported. 97 More controversial are reports of very large magneto-transport effects, the so-called ''giant planar Hall effects.''…”

Room-temperature spin injection and spin loss across a GaNAs/GaAs interface

“…They include incomplete spin alignment within a spin aligner, 8 spin loss during interlayer spin transfer, 11,12 and low efficiency of spin detection. [13][14][15][16] The conductivity mismatch at a ferromagnetic metal-semiconductor interface has now been identified as a major cause for spin loss, which can be improved by inserting a tunneling barrier. 9 Structural defects such as stacking faults at a semiconductorsemiconductor interface were also shown to lead to strong spin scattering at low temperatures.…”