JPH04112592A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To reduce leakage currents to a clearance layer, and to improve the injection efficiency of currents to an active quantum layer by introducing a specific high-resistance semiconductor layer into the clearance of the active quantum layer. CONSTITUTION:An Fe-doped high-resistance InP layer having 10<7>OMEGAcm or more or an Fe-doped high-resistance InGaAsP clearance layer (a compositional wavelength of 1.15mum) 13 is grown through an MOCVD method, thus concentrating currents injected to an active layer to a quantum fine line having optical gains and a quantum box 2 because the currents injected to the active layer cannot be made to flow through the high-resistance clearance layer 3 in a quantum fine line laser or a quantum box laser. Accordingly, reactive currents are reduced sufficiently, and the injection efficiency of currents is improved while optical gains and differential gains as the gradients of optical gains to injection currents can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor element for optical communication and an ultra-high speed semiconductor electronic device.

[Conventional technology]

Conventional methods for manufacturing multidimensional quantum structure lasers include a method of processing an active quantum structure and then filling the gap with a semiconductor layer, and a recent method of selectively growing an active quantum structure directly on a semiconductor substrate.

The former is discussed in IEICE Technical Report JOQE89-1115.

[Problem to be solved by the invention]

However, in the above conventional technology, sufficient consideration is not given to the efficiency of current injection into the active quantum layer, and current leakage due to the small electrical resistance of the interstitial layer of the active quantum structure causes the interstitial layer to oscillate. The expected multidimensional quantum size effect was not obtained.

An object of the present invention is to realize a multidimensional quantum size effect by reducing the reactive current flowing through the interstitial layer and increasing the efficiency of current injection into the active quantum layer.

[Means to solve the problem]

In order to achieve the above object, the present invention introduces a high-resistance semiconductor layer into the gap between active quantum layers to reduce leakage current to the gap layer and increase current injection efficiency into the active quantum layer.

The resistivity of the high-resistance layer is 10 7 to 10 9 Ω■, which is 10 2 to 20 3 times the resistivity of the active quantum layer, and is therefore extremely effective in increasing current injection efficiency.

[Effect]

The current blocking function of the high-resistance semiconductor layer will be explained below.

In the quantum wire laser or quantum box laser shown in FIG. 1, the current injected into the active layer cannot flow through the high-resistance gap layer, so it is concentrated in the quantum wire or quantum box that has an optical gain. Therefore, conventionally, the reactive current leaked to the low resistance gap layer is sufficiently reduced, and the current injection efficiency is greatly improved, and the optical gain, which is essential for laser oscillation, and the differential gain, which is the slope of the optical gain with respect to the injection current, are increased. In order to realize quantum wire lasers and quantum box lasers, it is essential to increase the optical gain and differential gain, and this can be achieved by introducing the high-resistance semiconductor layer into the gap layer.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 In FIG. 2, n-type nGaAs is deposited on an n-InP substrate.
P (composition wavelength 1.15 μm) guide layer 1100n, 1
-1nGaAs active layer 10nm, protective layer (composition wavelength 1.
15 μm) 5 nm thick by MOCVD method. Periodicity 1-O by lithography and etching
After forming the thin wire structure 7 of nm or less, MOCVD is performed again.
Fe-doped high-resistance InP layer or Fe-doped high-resistance InGaAsPrjl gap layer (composition wavelength 1, 15 μm)
Grow 3.

Here, in MOCVD growth on a substrate with unevenness with a period of several 1100 nanometers or less, the depressions are filled in first, so
By controlling the growth time during thin wire embedding growth, it is possible to perform embedding growth only in the thin wire gaps. Next, P-InGaAs P4 (composition wavelength 1.15μ
m) Grow a p-InP cladding layer of 100 nm and 51 μm. Form the BH structure and electrodes to create a device.

According to this embodiment, since leakage current to the quantum wire gap layer can be prevented, both optical gain and differential gain increase, and this effect allows for a low threshold current of less than 1 mA and a high speed of about 4 times or more than that of the conventional method. Direct modulation becomes possible.

Embodiment 2 In FIG. 3, a quantum wire-〇FB laser can be realized by introducing a diffraction grating 6 having a period equivalent to the gain peak wavelength of the quantum wire active layer into the structure of Example 1.

According to this example, in addition to laser characteristics comparable to those of Example 1, single wavelength oscillation and a spectral linewidth less than half of the conventional one can be obtained.

Example 3 In FIG. 4, an Fe-topped high-resistance InP layer or an Fe-doped high-resistance InGaAs layer is used as the active layer of Example 1.
A quantum box 8 having a gap layer made of P (composition wavelength 1.15 μm) is introduced.

According to this embodiment, since leakage current to the quantum box gap layer can be prevented, both the optical gain and the differential gain increase, and due to this effect, as well as the extremely low threshold current of 1 μA or less, the conventional 6
Direct modulation that is about twice as fast as this becomes possible.

Example 4 In FIG. 5, a diffraction grating 6 having a period corresponding to the gain peak wavelength of the quantum box active layer is added to the structure of Example 3.
By introducing this, a quantum box-DFB laser can be realized.

According to this example, in addition to laser characteristics comparable to those of Example 3, it is possible to achieve single wavelength oscillation and a spectral linewidth that is one to two orders of magnitude smaller than that of the conventional laser.

〔Effect of the invention〕

The present invention is extremely effective in increasing current injection efficiency in quantum wire lasers and quantum box lasers. According to this invention, a quantum wire laser and a quantum box laser can be realized.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, and FIGS. 2 to 5 are cross-sectional perspective views of essential parts of a laser device according to an embodiment of the present invention. 2... Quantum wire or quantum box, 3... High resistance semiconductor gap layer, 6... Diffraction grating, 7... Quantum wire, 8...
quantum box.

Claims (1)

[Claims] 1. A multidimensional quantum structure laser such as a quantum wire laser or a quantum box laser, characterized in that the interstitial layer of the quantum wire or the quantum box is a semi-insulating semiconductor with a resistivity of 10^7 Ωcm or more. semiconductor laser. 2. A semiconductor laser according to claim 1, which is capable of highly efficient current injection into active quantum layers such as quantum wires and quantum boxes. 3. A semiconductor laser according to claim 1, characterized in that it has a diffraction grating with a period corresponding to the gain peak wavelength of the quantum active layer and oscillates at a single wavelength. 4. In an electron/electronic wave device using a quantum wire/quantum box structure, the interstitial layer of the quantum wire/quantum box has a resistivity of 10^
An electronic/electronic wave device characterized by being a semi-insulating semiconductor with a resistance of 7 Ωcm or more.