PAM-XIAMEN Offers InAsP layer

PAM-XIAMEN Offers InAsP layer

Ternary semiconductor thin films of InAsP epitaxially on InP can be offered to customers for developing a better and a more reliable distributed feedback (DFB) lasers. Our InAsP layer has excellent properties, the size of the InAsP layer can be controlled by the height of the corrugation, and the arsenic composition in the InAsP layer can be controlled by the AsH/sub 3/ partial pressure. The results of TEM, EDS and PL show that InP is suitable as the buffer layer between the InAsP layer and MQW active layer. Fabricated 1.3 /spl mu/m DFB lasers which have an InAsP layer as an absorptive grating have shown low threshold current and high slope efficiency from -40-+85/spl deg/C, and high reliability has been demonstrated. Following is the epistructure of InAsP on InP substrate from PAM-XIAMEN:

Ternary semiconductor thin films of InAsP on InP

1. InAsP / InP Heterrostructure

ITEM x/y Doping carrier conc.(cm3) Thickness(um wave length(um) Lattice mismatch
InAs(y)P 0.25 none  –
In(x)GaAs 0.63 none 1.0*10^17 1.9 600<>600
InAs(y)P 0.25 S 2.5  –
InAs(y)P 0.05->0.25 S  –
InP S  –
Substrate: InP   S (1-3)*10^18 ~350  –

2. About Ternary Semiconductor – InAsyP1-y

The band gap of the III–V ternary semiconductor InAsyP1-y can be continuously changed from 1.35eV of InP to 0.36eV of InAs, and its emission wavelength can cover the near-infrared to mid-infrared bands, which is an important material used in long-wavelength optoelectronics. For example, the InAsP-InP strained heterostructures grown by epitaxy as the active regions of 1.06, 1.3 and 1.55 micron optoelectronic devices can well improve the device performance.

Compared with the InxGa1-xAsyP1-y / InP material system, the InAsyP1-y / InP heterostructure has a large conduction band discontinuity, which is very beneficial for long wavelength laser diodes under high temperature conditions and electroabsorption modulators operating at high optical power. Therefore, the InAsP ternary materials have important applications in optical fiber communication.

For the epitaxial growth of InAsyP1-y / InP heterojunction materials, the growth rates of InAsyP1-y and InP are determined by the beam current of In. And the composition ratio of InAs and InP in the InAsyP1-y ternary system is determined by the As and P beam currents. The composition ratio of the InAsyP1-y ternary semiconductor is very important because it determines the forbidden band width of the InAsyP1-y single crystal, which in turn affects the operating wavelength of the optoelectronic device.

3. Growth and Characterization of Strained InAsP / InP Quantum Well Structure

Crystal growth and material characterization of InAsP strained quantum-well structures and its application to 1.3 um lasers were investigated in term of threshold current reduction and high temperature operation. Layer thickness fluctuation caused by the large elastic strain can be eliminated by decreasing growth temperature. Although temperature dependence of the threshold current is expected to be improved by large conduction band discontinuity of InAsP ternary compound semiconductor, small number of well due to the critical layer thickness compensates for the improvement. To avoid the problem, tensile-strained InGaP barriers as well as very thin InP intermediate layers were applied.

The device with InAsP/InP/InGaP/InP triple quantum well as an active region showed low threshold current density of 300 A/ cm2 and the reduction of threshold current density of the device is significant at shorter cavity length region. It is confirmed that InGaP barrier, instead of conventional GaInAsP, is effective to carrier confinement if the active region has small number of wells. The highest characteristic temperature T 0 of 117 K was also reported in the similar device structure. Besides these excellent performances, good aging characteristic is verified. Very small changing in operating current to obtain 10mW at 50℃ is confirmed for both strained and strain-compensated InAsP/GaInAsP lasers.

4. Q&A for Growing InAsP Ternary Semiconductor Compounds on InP

Q1: Graded InAsP buffer layer (typ. 1-5um), n+ doped, what is the doping concentration.

A: 0.1-1.0e18   

Q2: InGaAs layer, 2-3um – 1.9um cutoff what is the exact thickness? 

A: 3.0um   

Q3: InAsP layer, 0.5-1um – lattice matched to the InGaAs layer 

A: InAsP buffer layer has as main function to reduce the dislocation density in the material, thickness should follow from your internal work

Q4: What is the roughness of surface required? 

A: We never characterized this material towards roughness since it has cross-hatch; electrical characteristics of the processed material towards PIN diodes (dark current) is much more important our roughness should be on about Ra=10nm

Q5: What is the EPD? EPD <=500/cm2     

A: The substrate EPD should be <=500/cm2, EPD of total wafer <=10^6/cm2

Q6: What is the quantity? 

A: For evaluation: 2 or 3, after qualification: 5-10.

Q7: Could you please advise the substrate orientation?

A: The similar remark as for the InAsP buffer layer and roughness; another supplier was using (100) 2deg off <110>+/-0.1, our substrate orientation should be (100) +/-0.5 deg.

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For more information, please contact us email at victorchan@powerwaywafer.com and powerwaymaterial@gmail.com.

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