IBPOWER Kick off meeting – 07/02/08

Specific issues relating to plasma-MBE

Growth under group III-rich versus group V-rich conditions

Control of composition is different from conventional MBE growth

Strong polarisation fields for wurtzite nitrides

Controlled p-doping of InGaN

IBPOWER Kick off meeting – 07/02/08

GaN MBE growth kinetics

Heying et al, Appl Phys Lett 77 (2000) 2885

In would be similar, but at a lower temp.

IBPOWER Kick off meeting – 07/02/08

Growth under N-rich conditions

IBPOWER Kick off meeting – 07/02/08

Growth under optimum conditions

IBPOWER Kick off meeting – 07/02/08

Composition control

Conventional MBE:- fix In:Ga ratio and use excess group V flux

For plasma MBE under group III richconditions:- fix Ga:N ratio and useexcess In – excess In will re-evaporate

IBPOWER Kick off meeting – 07/02/08

Controlled doping of InGaN?

Recent evidence at ICNS7 for InN p-n junction

In may enhance Mg solubility in InGaN

Depth of Mg in InGaN may be < 200meV

Influence of inversion and accumulation layers at the surface Veal et al JCG 288 (2006) 268

For InN there is strong electron accumulation at the surface due to pinning of the Fermi energy high in the conduction band – This will be an issue for P-doping

IBPOWER Kick off meeting – 07/02/08

Polarisation fields

In GaN the polarisation fields enhance electron andhole mobility to the surface and substrate

In-rich InGaN will be very different due to the surface accumulation layer

IBPOWER Kick off meeting – 07/02/08

Proposed programme- questions?

What In content should we aim for initially? The calculations suggest the Mn level is optimum for 15% Ga is that correct?

What are the optimum thicknesses for the P-i-N layers?

Should the top contact be graded towards a higher band-gap to ensure photons are absorbed in the Mn doped InGaN region?

Choice of substrate – sapphire, GaAs or GaN templates?

Should we consider cubic InGaN as an alternative?

IBPOWER Kick off meeting – 07/02/08

Initial growth programme

Growth of InGaN with the correct In content and correct polarity using AlN buffer layers.

P & N-doping of InGaN with Mg and Si

Mn doping of InGaN

P-i-N structures with and without Mn

Initial layers available for etching studies by partners