Quantum well device with ESD endurance and method of forming...

Details Quantum well device with ESD endurance and method of forming... Quantum well device with ESD endurance and method of forming...

2000-08-22

2004-04-13

Jackson, Jerome (Department: 2815)

Active solid-state devices (e.g., transistors, solid-state diode

Thin active physical layer which is

Heterojunction

C257S015000

Reexamination Certificate

active

06720571

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a quantum well device and a method of forming the same, and more particularly, to a quantum well device with electro-static discharge (ESD) endurance and a method of forming the same.
BACKGROUND OF THE INVENTION
For recent years, a multiple quantum well structure has been extensively applied in the light emitting semiconductor structure. Various improved multiple quantum well structures have been also researched and developed. A modern multiple quantum well structure is frequently applied to a light emitting diode or a laser diode.
FIG. 1
is a schematic diagram of a conventional quantum well device
10
. The conventional quantum well device
10
includes a GaAs substrate
12
of a first conductivity type and a GaAs buffer layer
14
on the GaAs substrate
12
. An AlGaInP cladding layer
16
of the first conductivity type is formed on the GaAs buffer layer
14
. A lower confining layer
18
is formed on the AlGaInP cladding layer
16
. An active layer
20
is formed on the lower confining layer
18
. An upper confining layer
22
is formed on the active layer
20
. An AlGaInP cladding layer
24
of a second conductivity type is formed on the upper confining layer
22
. Finally, a cover layer
26
of the second conductivity type is formed on the AlGaInP cladding layer
24
, wherein the cover layer
26
is a window layer or an ohmic contact layer.
FIG. 2
is a schematic diagram of the active layer
20
shown in FIG.
1
. The active layer
20
of the conventional quantum well device
10
adopts a multiple quantum layers structure which is formed by alternately stacking a plurality of barrier layers
19
and a plurality of quantum well layers
21
. Each barrier layer
19
and each quantum well layer
21
are made of undoped AlGaInP.
FIG. 3
is an ESD performance test diagram of the quantum well device
10
shown in FIG.
1
. For a long time, ESD problems coming from human-body mode or machine mode have existed in the quantum well device
10
. Particularly for the quantum well device
10
having an emitting light wavelength between 570 nm and 650 nm, the accumulated failure percentage of the quantum well device
10
nears almost 100% if a failure voltage resulting from ESD is raised from 0V to 3 kV according to the ESD performance test results. Therefore, U.S. Pat. No. 5,116,767 discloses a laser diode having a passivation layer to improve the electric stress induced by artificial or mechanical ESD. However, the passivation layer places burden over the technology of epitaxy process and increases cost. Therefore it is not widely applied.
SUMMARY OF THE INVENTION
To overcome the above problems, the present invention discloses a quantum well device and a method of forming the same. The quantum well device includes alternately stacked n layers of quantum well layers and n layers of barrier layers, wherein the quantum well layers and barrier layers are alternatively doped with dopant, and n is a positive integer. The quantum well device of the above structure is usually referred to as an active layer in a light emitting device.
The method of forming a quantum well device includes the steps of alternately stacking n layers of quantum well layers and n layers of barrier layers, and during the stacking step, alternatively doping the quantum well layers and barrier layers with dopant, wherein n is a positive integer.
In other embodiments, the quantum well device further includes a substrate, a buffer layer, a lower cladding layer, a lower confining layer, an upper confining layer, an upper cladding layer, and a cover layer.
The dopant of the quantum well device controls the breakdown voltage and output intensity of the quantum well device and consequently avoids artificial and mechanical ESD failure. In embodiments, the dopant is n-type dopant including Te, Se or Si. In another embodiments, the dopant is p-type dopant including Mg, C or Zn. A concentration of the dopant is preferably between 5×10
6
/c.c and 3×10
18
/c.c.


REFERENCES:
patent: 5502739 (1996-03-01), Kidoguchi et al.
patent: 5521935 (1996-05-01), Irikawa
patent: 5563423 (1996-10-01), Wu et al.
patent: 5959307 (1999-09-01), Nakamura et al.
patent: 0 210 616 (1987-02-01), None
patent: 09232666 (1997-09-01), None
patent: 10135573 (1998-05-01), None
Mawatari et al., “Spectral Linewidth and Linewidth Enhancement Factor in 1.5&mgr;m Modulation-Doped Strained Multiple-Quantum-Well Lasers,” Jpn. J. Appl. Phys., vol. 33 (1994), pp. 811-814.
Shimizu et al., “1.3-&mgr;m InAsP n-Type Modulation-Doped MQW Lasers Grown by Gas-Source Molecular Beam Epitaxy,” IEEE Journal of Selected Topics in Quantum Electronics, vol. 5, No. 3, May/Jun. 1999, pp. 449-456.

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