05/07/18 Optical Characterization of High-Mobility Quantum Well with Low-density Modulation-Doping

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05/07/18Optical Characterization of
High-Mobility Quantum Wellwith Low-density
Modulation-Doping

• Toshiyuki Ihara

Abstract. I measured PL and PLE spectra of
high-mobility 33nm quantum well with low-density
modulation doping. The sample 03-11-05.1 contains
2D electron gas (2DEG) of 5.9x1010cm-2 without
parallel conduction. On the contrary, the sample
03-24-05.3 contains 2DEG of 3.5x1010cm-2 with
parallel conduction. The decrease of the 2D
electron density due to Indium solder is clearly
observed PL scan of 03-24-05.3, where the exciton
peak appears at low electron density. The PLE
spectra depends on the sample and also on the
position (near / far from In solder). We need
further investigation to know which is the main
origin that causes the spectral differences, the
electron density or the parallel conduction.
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Sample information
? LP means Low density Parallel
conduction
Sample name 03-11-05.1 03-24-05.3 LP
Quantum well 330ÅGaAs 330ÅGaAs
Barrier 10 AlGaAs 10 AlGaAs
Si doping 3x1011cm-2 (7.4A x 11sec) 3x1011cm-2 (7.4A x 11sec)
Set back 800Å 1500Å
Electron density 5.9x1010cm-2 3.5x1010cm-2
Parallel conduction no yes
Indium annealing 30s 30s
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PL scan near Indium solder
The decrease of 2D electron density around Indium
solder is clearly observed in low-density doped
quantum well (03-24-05.3 LP).
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PLE spectra of both samples
What causes the difference of PLE spectra, the
electron density or parallel conduction?
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PLE spectra measured near / far from In solder
Though there are interesting differences,the
mechanism is still unclear
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Measurements of conductivity
There are two problems ?Resistance is
large.?Success rate is low.Further investigation
is needed (shorter annealing time , use InSb etc.)
To be continued