JPH05110132A - Light-emitting semiconductor element - Google Patents

Abstract

PURPOSE:To improve a quantum efficiency by having a compound light-emitting semiconductor part held between different conductive type semiconductor layers on a semiconductor substrate with the substrate surface directed to the face (111), by doping rare earth ion to the semiconductor light-emitting part and by introducing distortion into the light-emitting semiconductor part. CONSTITUTION:A light-emitting semiconductor element is manufactured by a molecular beam epitaxy method. The transition energy level 27 of the parent material of Er-doped distortion quantum well layer 13 is mainly determined by the composition of InGaAs, the degree of lattice mismatching, quantum well thickness, piezo-internal electrolysis, etc. In addition to the piezo-internal electrolysis by distortion, an internal electrolysis by PN junction is applied to the Er-doped distortion quantum well layer 111 in the same direction to further increase the excitation of Er by carrier. A stripe electrode is formed in this layer structure so that a single longitudinal mode oscillation is obtained. A threshold current is about the half of the threshold current of the same structure laminated on the face (100) and the increase of excitation of Er ions is recognized by piezo-electric effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high performance and highly uniform semiconductor light emitting device.

[0002]

2. Description of the Related Art Conventionally, semiconductor light emitting devices have mainly utilized optical transitions between semiconductor band bands and quantum levels of a quantum well structure. In this type of semiconductor light emitting device, the purity of the light emitting layer,
The controllability of the composition, layer thickness, etc. greatly affected the characteristics of the device.
On the other hand, when rare earth ions are added to the semiconductor,
A semiconductor light emitting device has been reported that excites rare earth ions with the energy of a hole pair and uses an emission spectrum with a narrow wavelength, which is unique to each ion (for example, Applied Physics Letter WT Tsang et al. A
ppl. Phys. Lett. Volume 49, (1986)
Page 1686). In this light emitting device, the transition between the excited state and the ground state of the 4f shell electron system is utilized, and since the 4f electron system is not directly involved in the bond of the solid, the emission wavelength is not largely influenced by the type of the host. So, for example, Ga
In the semiconductor laser in which the InAsP matrix is doped with Er ³⁺ , the in-plane uniformity of the emission wavelength on the wafer does not depend on the semiconductor matrix material, so it has extremely high uniformity, and the oscillation wavelength temperature change is about 1 angstrom per degree Celsius. And small.

[0003]

As described above, the rare earth-doped semiconductor light emitting device has various excellent characteristics, but the greatest drawback thereof is that the luminous efficiency is generally low. For example, the quantum efficiency of Er-doped GaAs grown by the MBE method at room temperature is as low as about 10 ^-6 . This is because this light emitting device requires an energy transfer process between the electron-hole pair and the rare earth ion, and the magnitude of this process affects the quantum efficiency.

An object of the present invention is to provide a rare earth-doped semiconductor light emitting device having high quantum efficiency.

[0005]

[Means for Solving the Problems] Means provided by the present invention are: a semiconductor substrate having a substrate plane orientation of (111) plane;
A semiconductor light emitting device having a compound semiconductor light emitting portion sandwiched between semiconductor layers of different conductivity types, characterized in that the semiconductor light emitting portion is doped with rare earth ions and strain is introduced into the semiconductor light emitting portion. is there.

[0006]

When a compound semiconductor strained layer having a lattice constant different from that of the substrate is laminated on the (111) plane, a piezoelectric effect occurs due to lack of crystal inversion symmetry, and an internal electric field is generated in the laminating direction. For example, in the InGaAs system, an internal electric field of about 10 ⁵ V / cm is generated for a lattice strain of 1%. When electrons and holes are injected into this layer, carriers are accelerated in different directions by the internal electric field. If the internal electric field is large enough, the carriers can pump the rare earth ions to an excited state by collision. The electric field required for pumping is Er of about 10 ⁵ V / cm in the InP crystal, which can be sufficiently created in the compound semiconductor strained layer. The electron-hole pairs injected into the compound semiconductor strained layer by the above mechanism can effectively transfer energy to rare earth ions,
The quantum efficiency can be increased.

[0007]

1 is a structural diagram of an embodiment of a semiconductor light emitting device according to the present invention. This is manufactured by the molecular beam epitaxy method. The manufacturing procedure is Zn-doped InP (111) B.
Of Be-doped (5 × 10 ¹⁷
cm ⁻³ ) In _0.52 Al _0.48 As clad layer 12 of 1 μm
In _0.65 Ga _{0.35 which is} laminated and has a lattice mismatch of about 1% with InP and is Er ^- doped at 1 × 10 ¹⁸ cm ^-3.
35 Å As layer 13, non-doped In _0.52 Al _0.48 As
Layers 14 of 150 Å are alternately laminated for 4 periods, and further Si-doped (5 × 10 ¹⁷ cm ⁻³ ) In _0.52 Al _0.48 As clad layer 15 is laminated to 1 μm, and finally Si-doped (3 × 10 ¹⁸
cm ⁻³ ) In _0.53 Ga _0.47 As cap layer 16 to 0.5
μm is laminated. The off-substrate is used as the substrate in order to prevent twins from being generated during stacking. In _0.65 Ga _0.35 As
Layer 13 has a lattice mismatch of about 1% but a stack thickness of 35Å
It is small and within the critical film thickness, and misfit dislocations do not occur.

FIG. 2 is a band diagram of the above laminated structure.
The transition energy level 27 of the matrix of the Er-doped strained quantum well layer 13 is mainly determined by the composition of InGaAs, the degree of lattice mismatch, the quantum well thickness, the piezoelectric internal electric field, and the like. In this embodiment, the voltage is about 0.8 eV at room temperature. The Er-doped strained quantum well layer 111 has a piezoelectric internal electric field of about 100 KV /
In addition to the cm, an internal electric field of about 70 due to the PN junction in the same direction.
KV / cm is applied to further enhance Er excitation by carriers. A stripe electrode is formed on this layer structure, and room temperature pulse operation is measured. Oscillation wavelength is 1.54
μm, single longitudinal mode oscillation is obtained. The threshold current is about half of the threshold current of the same structure laminated on the (100) plane for comparison, and the excitation extension of Er ions is confirmed by the piezoelectric effect. Further, in this semiconductor light emitting device, since the gain is concentrated on the transition wavelength of Er ions, the side mode suppressing effect at the time of oscillation is remarkable, and the ratio is about 30 dB.

Although only one embodiment has been described above, the present invention is not limited thereto. The semiconductor growth method may be a liquid phase growth method, a metal organic vapor phase growth method, or the like. The rare earth ions to be doped are also E
It is not limited to r and may be Yb, Nb, or the like. The material system to be laminated is also InGaAsP system, InGaSb system, etc. III-V
Group II or II-VI group compound semiconductors such as ZnSSe and ZnTe may be used. Further, if the substrate used is the (111) plane, either the A plane or the B plane may be used, and if the strained semiconductor light emitting portion is a compound semiconductor, it may be an element semiconductor such as Si. The strain of the strained semiconductor light emitting portion may be tensile or compressive. The same effect can be achieved in other semiconductor light emitting devices such as semiconductor light emitting diodes.

[0010]

As described above, according to the semiconductor light emitting device of the present invention, a rare earth-doped semiconductor light emitting device having high luminous efficiency can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a band structure in the embodiment of FIG.

[Explanation of symbols]

11 Zn-doped InP (111) B substrate 12 Be-doped In _0.52 Al _0.48 As clad layer 13 Er-doped In _0.65 Ga _0.35 As layer 14 Non-doped In _0.52 Al _0.48 As layer 15 Si-doped In _0.52 Al _0.48 As clad layer 16 Si-doped In _0.53 Ga _0.47 As cap layer 27 Transition energy

Claims (1)

[Claims] 1. A semiconductor light emitting device having a compound semiconductor light emitting portion sandwiched between semiconductor layers having different conductivity types on a semiconductor substrate having a substrate plane orientation of (111) plane, wherein the semiconductor light emitting portion has a rare earth element. A semiconductor light emitting device, characterized in that it is doped with ions and strain is introduced into the semiconductor light emitting portion.