JPH05283743A - Semiconductor light-emitting element - Google Patents

Abstract

PURPOSE:To obtain a rare earth-doped semiconductor light-emitting element having a high quantum efficiency by a method wherein rare earth ions are doped to a first semiconductor. CONSTITUTION:An Si-doped In0.52Al0.48As clad layer 12 is laminated on an Sn-doped InP substrate 11 and a semiconductor superlattice structure formed by laminating alternately Er-doped InP layers 13 and In0.52Al0.48As layers 14 six periods is laminated thereon. Moreover, a Be-doped In0.52Al0.48As layer 15 is laminated thereon and if a Be-doped In0.53Ga0.47As cap layer 16 is laminated, a stacked band structure is formed according to an anion rule because the group V elements of the InP layers and the InAlAs layers are different from each other. Accordingly, electrons 22 are easily captured by Er<3+> traps 25 in the forbidden bands of the InP layers and when the electrons recombine with holes 24 in an InAlAs layer 23, Er 4f electrons are transmitted at a high efficiency to an excited state and a rare earth-doped semiconductor light- emitting element having a high luminous efficiency is obtained.

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 been mainly used for semiconductor devices.
Utilizing optical transitions between quantum levels in the band and quantum well structures
Was. In this type of semiconductor light emitting device, the purity of the light emitting layer,
The controllability of composition and layer thickness greatly influences the characteristics of the device.
It was On the other hand, by adding rare earth ions to the semiconductor,
The rare-earth ion is excited by the energy of the child-hole pair and
Semi-narrowed emission spectrum characteristic of ions
Conductive light emitting devices have been reported (eg, applied
Physics Letter W. T. Tsang eta
l. , Appl. Phys. Lett. Volume 49,
(1986) page 1686). 4 in this light emitting device
Utilizing the transition between the excited and ground states of the f-shell electron system
The 4f electron system was not directly involved in solid state binding
Therefore, the emission wavelength is not significantly affected by the type of matrix. This
Therefore, for example, Er in GaInAsP matrix ³⁺Dope
In semiconductor lasers, the uniformity of the emission wavelength within the wafer is semi-conducting.
Since it does not depend on the base material, it has extremely high uniformity.
The temperature change of the oscillation wavelength is 1 angstrom per degree Celsius
Small and small.

[0003]

As described above, the rare earth-doped semiconductor light emitting device has various excellent characteristics, but the biggest problem 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]

A semiconductor light emitting device of the present invention has a semiconductor light emitting layer sandwiched between semiconductor layers having different conductivity types, and the semiconductor light emitting layer has a film thickness equal to or less than an average free path of electrons. A semiconductor superlattice in which the first and second semiconductors having the following are alternately laminated at least one period, and the energy value of the conduction band lower end of the first semiconductor is lower than the conduction band lower end and the valence band upper end of the second semiconductor. And the energy value at the top of the valence band of the second semiconductor is between the bottom of the conduction band and the top of the valence band of the first semiconductor, the first semiconductor Is doped with rare earth ions.

[0006]

[Function] Most rare earth ions are trivalent, II
When it is replaced with a group III atom of a group IV compound semiconductor, it acts as an isoelectron trap and does not itself emit an electron but traps an electron in the conduction band. The electrons trapped in the isoelectron trap are recombined with holes in the valence band,
The f-shell electron system of rare earth ions is transited to the excited state. Therefore, the probability of transferring the energy of the electron-hole system in the semiconductor to the excited state of the f-shell electron system is such that the electron-hole radiative recombination in the semiconductor matrix is suppressed, and the electrons in the conduction band are all absorbed. It can be enlarged by trapping it in rare earth ions and recombining it through the Auger process. Generally, in a so-called type II semiconductor superlattice in which the lower end of the conduction band and the upper end of the valence band are alternately arranged in two semiconductor superlattices, electrons and holes are spatially separated. The radiative recombination of the electron-hole system is suppressed and the electrons have a relatively long recombination lifetime. Therefore, if one semiconductor layer in which electrons are localized is doped with rare earths, the probability of electrons being trapped in rare earths increases, and the probability of 4f shell excitation of rare earths also increases. Therefore, the semiconductor light emitting device of the present invention realizes a highly efficient energy transfer process between an electron-hole pair and a rare earth ion, and realizes a high quantum efficiency.

[0007]

The present invention will be described below with reference to the drawings. FIG. 1 is a structural diagram of a semiconductor light emitting device according to an embodiment of the present invention. This is manufactured by the molecular beam epitaxy method.
The manufacturing procedure is as follows: Si-doped (5 × 10 ¹⁷ cm ⁻³ ) In _0.52 Al _0.48 As clad layer 12 is laminated on the Sn-doped InP substrate 11 by 1 μm, and 100 Å Er-doped (1 × 10 ¹⁸ cm 2 ^-3 ) InP layers 13 and 1
A semiconductor superlattice structure in which six layers of In _0.52 Al _0.48 As layers 14 of 00 angstroms are alternately laminated is laminated, and Be-doped (5 × 10 ¹⁷ cm ⁻³ ) In _0.52 Al is laminated thereon.
_{The 0.48} As layer 15 is laminated in a thickness of 1.5 μm, and finally the Be-doped (1 × 10 ¹⁹ ) In _0.53 Ga _0.47 As cap layer 16 is laminated in a thickness of 0.1 μm. Since InP and InAlAs have different V group elements, they form a stacker type band structure according to the anion rule. FIG. 2 is a band diagram of the above laminated structure. Electrons 22 are accumulated in the Er-doped InP layer 21 during current injection, and holes 24 are accumulated in the InAlAs layer 23. As described in the action section, in this structure, electrons are easily trapped by the Er ³⁺ trap 25 in the forbidden band of InP, and the 4f electron system of Er is excited when recombining with holes in the InAlAs layer. Transition to a state with high efficiency.

This excited state is a light of a specific wavelength (1.5
It transits to the ground state while emitting (μm light). In the semiconductor light emitting device according to the present embodiment, the emission intensity from Er is about ten times stronger than that of the semiconductor light emitting device using the Er-doped InGaAs layer for the same current injection amount.

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 not limited to Er and may be Yb, Nd or the like. The material system to be laminated is also InP, AlAsSb, GaInP.
And AlAs, etc. may be used.

[0010]

As described above, according to 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 structural diagram of an embodiment of the present invention.

FIG. 2 is a band diagram of a semiconductor light emitting layer of the semiconductor light emitting element shown in FIG.

[Explanation of symbols]

13 Er-doped InP layer 14 In _0.52 Al _0.48 As layer 21 Er-doped InP layer 23 InAlAs layer 24 Er ³⁺ trap

Claims (1)

[Claims] 1. A semiconductor light-emitting layer sandwiched between semiconductor layers having different conductivity types, wherein the semiconductor light-emitting layer comprises alternating first and second semiconductors having a film thickness equal to or less than the mean free path of electrons. A semiconductor superlattice in which at least one period is stacked, the energy value of the conduction band lower end of the first semiconductor is between the conduction band lower end and the valence band upper end of the second semiconductor, and the second semiconductor The energy value at the top of the valence band of the semiconductor is between the energy value at the bottom of the conduction band and the energy of the top of the valence band of the first semiconductor, and the first semiconductor is doped with rare earth ions. Semiconductor light emitting device.