CN102545059A - Semiconductor laser chip quantum well structure with P/N (phosphorus/ nitrogen) heterojunction - Google Patents

Abstract

The invention relates to a semiconductor laser chip quantum well structure with a P/N (phosphorus/ nitrogen) heterojunction. The quantum well structure comprises an N type indium phosphide layer, a non-doped quantum well zone and a P type indium phosphide layer along a growth direction of a semiconductor, and is characterized in that: one layer of non-doped indium phosphide layer is introduced in the N type indium phosphide layer and has the thickness of 0.1-1 micrometer; and an N type doped indium phosphide layer between the non-doped indium phosphide layer and the non-doped quantum well zone has the thickness of 0-2 micrometers. The semiconductor laser chip quantum well structure with the P/N heterojunction has the main three advantages that: 1, the reliability of a laser chip is improved, and the stability of a data network is enhanced; 2, the anti-static requirement on chip production equipment is reduced, and thus the equipment cost and the chip cost are reduced; and 3, the production environment requirement on downstream chip packaging manufactures is reduced, convenience is provided for clients to reduce cost, and the reliability is improved.

Description

A kind of quantum well structure with semiconductor laser chip of P/N heterojunction

Technical field

The present invention relates to the design and the manufacturing of semiconductor chip, particularly a kind of quantum well structure with semiconductor laser chip of P/N heterojunction is to promote the reliability of high speed ridge waveguide type semiconductor chip of laser.

Background technology

Semiconductor laser chip is the most important device of modern optical communication network; All information all is to carry out being transferred to each corner, the world to information through fiber optic network after the opto-electronic conversion through chip of laser; Its main application fields has: fiber area networking (Local Area Network); Light networking storage (Storage Area Network); And Fiber to the home (Fiber-To-The-Home), and the cloud computing (Cloud Computing) that will change the human life style from now in 10 years.

The basic structure of existing chip of laser has two kinds; The ridge waveguide type with bury type heterojunction chip; The chip majority that speed surpasses more than 10,000,000,000 grades on the international market at present belongs to ridge waveguide type AlInGaAs complex chemical compound semiconductor laser chip; The structure of ridge waveguide cake core is as shown in Figure 1, from top to bottom comprises: P type metal electrode layer 1, P type doping indium phosphide semiconductor layer 2, non-doped with Al InGaAs semiconductor quantum well structures 3, N type doping indium phosphide semiconductor layer 4, N type doping indium phosphide substrate layer 5 and N type metal electrode layer 6.Wherein, the zone 3 of ridge waveguide cake core is the SQW zone of electronics and hole injection and generation photon.The InP of existing product mixes and the SQW design, and as shown in Figure 2, transverse axis is the semiconductor growing direction, and main region has the SQW zone and the p type inp layer of n type inp cladding layer, non-doping, and the longitudinal axis is charge carrier (electronics and hole) energy level.The shortcoming of this structure is: chip of laser is when bearing reverse static, and all electric fields are applied to the SQW zone of non-doping all, are very easy to cause the puncture of the regional semi-conducting material of chip SQW, thereby cause product failure.

The characteristic of chip of laser comprises two aspects, and one is the traditional performance index, comprises luminous power, wavelength, threshold current, modulation rate etc.; Another one then is a reliability index, mainly comprises antistatic property, useful life; The long-term failure rate of using, wherein, antistatic property is a very important reliability index; If it is bad; Will in the encapsulation of chip or use, produce great product failure, this will cause thrashing for national defence communication, great public work and international wire network, brings heavy losses and adverse effect for country, operator or individual.So, how to improve chip anlistatig reliability in producing, assemble, using, will be the problem that all manufacturers and user extremely pay attention to.

With respect to the semiconductor chip both positive and negative polarity; Its antistatic property comprises the antistatic and reverse antistatic threshold value of forward; Surpass its threshold value if be applied to the voltage of chip forward or negative sense, chip of laser internal semiconductor material will have permanent damage so, even cause the inefficacy at once of product.The antistatic threshold value of the forward of ridge waveguide laser chip generally can reach more than the 4000V, and reverse antistatic threshold value approximately has only 600V, wears voltage so then be to improve reverse resistance for ridge waveguide type laser antistatic property key.

Summary of the invention

The objective of the invention is to, a kind of quantum well structure of the novel semiconductor laser chip with P/N heterojunction is provided,, promote the reliability of chip of laser to reduce requirement to chip production equipment antistatic.

The present invention mainly is with the SQW in 3 and 4 zones among Fig. 1 and the inp semiconductor material component and the design again of mixing, and promotes the antistatic property of chip.

For realizing the foregoing invention purpose; The invention provides a kind of quantum well structure of novel semiconductor laser chip with P/N heterojunction; Described quantum well structure has the SQW zone and the p type inp layer of n type inp cladding layer, non-doping along the semiconductor growing direction; It is characterized in that; Introduce the phosphorization phosphide indium layer of the non-doping of one deck in the described n type inp cladding layer, its thickness is 0.1～1 micron, and the thickness of the phosphorization phosphide indium layer that the N type between the SQW zone of the phosphorization phosphide indium layer of the non-doping of this layer and non-doping mixes is 0～2 micron.

A kind of preferred as technique scheme, the thickness of the phosphorization phosphide indium layer of the non-doping in the described n type inp cladding layer is 0.1～0.5 micron.

Preferred as another of technique scheme, the thickness of the phosphorization phosphide indium layer that the N type between the SQW zone of the phosphorization phosphide indium layer of described non-doping and non-doping mixes is 0.1～0.5 micron.

As shown in Figure 3, be the indium phosphide zone of mixing in the N type, introduce the phosphorization phosphide indium layer of the non-doping of one deck, the thickness range of the phosphorization phosphide indium layer of this non-doping can be in 0.1～1 micrometer range, if exceed this scope, chip of laser is with regard to cisco unity malfunction; Can there be certain flexibility the position of the phosphorization phosphide indium layer of this non-doping, and rightmost can arrive the SQW next door, and Far Left can be away from SQW 2um.The thickness range that is to say the second layer is 0.1～1um, and the 3rd layer thickness can be 0～2um.Preferably, its thickness can from 0.1 to 0.5 micron wait, i.e. the 2nd layer among Fig. 3.And the 3rd layer of indium phosphide that remains the doping of N type of Fig. 3, its thickness range is 0.1 to 0.5 micron.

This design advantage is: when chip bears reverse electrostatic impact; Half the even more electric field strength can be distributed to the indium phosphide zone of non-doping; Be the 2nd layer among Fig. 3; And real substep can reduce to the electric field strength of SQW greatly, and therefore, regional injury can reduce static for the most important SQW of chip.

Because according to Poisson's equation (Poisson ' s equation), dE/dx=ρ/κ _sε ₀, the distribution of electric field strength changes with the difference of net charge area distribution.Wherein, E is an electric field strength, and ρ is a net charge density, K _sBe the semiconductor dielectric constant, ε ₀It is permittivity of vacuum.Fig. 4 a has shown the PIN N-type semiconductor N structure of a simplification.Suppose that transverse axis is non-mixing in the middle of the semiconductor layer (I) zero point, two depletion layers lay respectively at-(χ _p(the χ of)～- _i/ 2) and χ _i/ 2～χ _n.According to the depletion layer hypothesis, electrostatic charge density is distributed as:

$\mathrm{\ρ}=\left\{\begin{array}{cc}0& x\≤-x_p\\ {-\mathrm{qN}}_A& -x_p\≤x\≤x_i/2\\ 0& -x_i/2\≤x\≤x_i/2\\ {\mathrm{qN}}_D& x_i/2\≤x\≤x_n\\ 0& x\≥x_n\end{array}\right.$

Wherein, N _A, N _DBe respectively the doping content that the P type mixes and the N type mixes, q is an electron charge.So electric-field intensity distribution is:

$\mathrm{dE}/\mathrm{dx}=\frac{\mathrm{\ρ}}{{\mathrm{\κ}}_s{\mathrm{\ϵ}}_0}=\left\{\begin{array}{cc}0& x\≤-x_p\\ {-\mathrm{qN}}_A/{\mathrm{\κ}}_s{\mathrm{\ϵ}}_0& -x_p\≤x\≤{-x}_i/2\\ 0& -x_i/2\≤x\≤x_i/2\\ {\mathrm{qN}}_D/{\mathrm{\κ}}_s{\mathrm{\ϵ}}_0& x_i/2\≤x\≤x_n\\ 0& x\≥x_n\end{array}\right.$

Shown in Fig. 4 b, so find the solution electric-field intensity distribution, E (x)=∫ dE (x)=∫ (ρ/κ _sε ₀) dx, can obtain:

In view of electric field in the continuity of boundary, can see electric field remain unchanged in whole non-doped semiconductor zone (prerequisite supposes that non-doped semiconductor zone net charge is zero).In most of practical applications, based on various structure and technological design, always there is relative doped region net charge seldom in non-doped semiconductor zone.Therefore, electric field can be the linear distribution that very slowly changes in non-doped semiconductor zone.For heavily-doped semiconductor and light dope (or non-doping) interface (for example Fig. 2, structure shown in 3), since depletion width, (χ _i/ 2-χ _n) very narrow, Electric Field Distribution can be approximated to be vertical change (shown in the dotted line of Fig. 4 b) at boundary vicinity.That is to say that electric field mainly is distributed in non-doped region, be rectangular box-like shown in Fig. 4 b dash area.Can estimate non-doped semiconductor zone (x by electric-field intensity distribution _i/ 2≤x≤x _i/ 2) voltage drop.Approximate based on above-mentioned rectangular box, then

$E\left(x\right)=-\mathrm{dV}\left(x\right)/\mathrm{dx}\⇒V\left(x\right)=\underset{-x_i/2}{\overset{x_i/2}{\∫}}-E\left(x\right)\mathrm{dx}=E_{\mathrm{cons}\tan t}{x}_i$

Wherein, χ _iCan open up the effective width and the applied voltage in widely non-doping (or light dope) zone respectively with V.So far, can be very clear see that structural design of the present invention (Fig. 3) relatively and the advantage of ordinary construction (Fig. 2).Structure shown in Figure 3 is introduced the non-doping indium phosphide of one deck at n type heavily doped region, has increased χ effectively _iThereby under identical applied voltage situation, reduce the electric field in SQW zone effectively.

The invention has the advantages that, the quantum well structure of the semiconductor laser chip of the novel P/N of having heterojunction of the present invention mainly contain three a little: 1, promote the reliability of chip of laser, strengthen the stability at data networking; 2, reduce the requirement of chip production equipment antistatic, thereby reduce equipment cost in chip cost; 3, reduction is convenient to the client and is reduced cost for the production environment requirement of the Chip Packaging manufacturer in downstream, improves reliability.

Two following forms are respectively the reverse antistatic threshold value (reverse ESD threshold value) of new and old chip of laser:

The reverse antistatic threshold value of the old chip of laser of table 1:

The reverse antistatic threshold value of the new chip of laser of table 2:

Electrostatic impact surpasses threshold value, will cause damage to chip of laser.Contrast both measured values, shown in top two tables, the chip that adopts the application to manufacture and design, its reverse antistatic threshold value on average reaches more than the 1000V, promotes more than 60% than the threshold value of common chip, has greatly promoted chip reliability.

Description of drawings

Fig. 1 is the structural representation of the ridge waveguide cake core of existing laser;

Fig. 2 is the structural representation of existing InP doping and SQW;

Fig. 3 is the structural representation of InP doping of the present invention and SQW;

Fig. 4 a is the PIN N-type semiconductor N structural representation of simplifying;

Fig. 4 b is the sketch map that electric field can change in non-doped semiconductor zone.

Embodiment

Below in conjunction with accompanying drawing the present invention is further specified.Of the present invention through with reference to the accompanying drawings to the detailed description of the embodiment of the invention, of the present inventionly above-mentionedly will become clearer with other characteristics and advantage, wherein:

Structure of the present invention not only is applicable to the quantum well structure design of ridge waveguide type semiconductor chip of laser, also is applicable to the quantum well structure of burying type heterogeneous semiconductor chip of laser.So long as the semiconductor laser chip of P/N heterojunction is arranged, notion of the present invention can be suitable for.

Embodiment 1

The MOCVD method is adopted in the growth of wafer, and it is following that the present invention produces the case study on implementation of semiconductor chip:

The measurement result of SQW: compared to the common lasers chip, it is about 400 that the reverse antistatic threshold value of the new laser chip of producing based on this patent on average increases, and met or exceeded the rank of 1000V.

It should be noted last that above embodiment is only unrestricted in order to technical scheme of the present invention to be described.Although the present invention is specified with reference to embodiment; Those of ordinary skill in the art is to be understood that; Technical scheme of the present invention is made amendment or is equal to replacement, do not break away from the spirit and the scope of technical scheme of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (3)

1. quantum well structure with semiconductor laser chip of P/N heterojunction; Described quantum well structure has the SQW zone and the p type inp layer of n type inp cladding layer, non-doping along the semiconductor growing direction; It is characterized in that; Introduce the phosphorization phosphide indium layer of the non-doping of one deck in the described n type inp cladding layer, its thickness is 0.1～1 micron, and the thickness of the phosphorization phosphide indium layer that the N type between the SQW zone of the phosphorization phosphide indium layer of the non-doping of this layer and non-doping mixes is 0～2 micron.

2. the quantum well structure with semiconductor laser chip of P/N heterojunction according to claim 1 is characterized in that, the thickness of the phosphorization phosphide indium layer of the non-doping in the described n type inp cladding layer is 0.1～0.5 micron.

3. the quantum well structure with semiconductor laser chip of P/N heterojunction according to claim 1 and 2; It is characterized in that the thickness of the phosphorization phosphide indium layer that the N type between the SQW zone of the phosphorization phosphide indium layer of described non-doping and non-doping mixes is 0.1～0.5 micron.

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