InGaAsP / InP Double Heterostructure Wafer

InGaAsP / InP Double Heterostructure Wafer

The InGaAsP material epitaxially grown on the InP substrate is an important material for the fabrication of optoelectronic and microwave devices. The emission wavelength of InGaAsP / InP laser structure covers 1.0-1.7μm, covering two low-loss windows of 1.3μm and 1.55μm for silica fiber communication. Therefore, InGaAsP is widely used in the manufacture of important components in the field of optical fiber communication, such as modulators, lasers, detectors and so on. Epi wafer for laser diode of bulk 1.55um InGaAsP / InP grown from PAM-XIAMEN is as below, which includes very high doped and very thin tunnel junction layers:

InGaAsP / InP Wafer

1. Specifications of InGaAsP / InP Laser Wafer

No. 1 Laser Diode Epi Strcuture PAM170919-INGAASP

Name Material Thickness [nm] Doping Strain PL [nm] Bandgap [eV] Notes
Bonding Layer InP 10     1.34  
Supperlattice InP      
  InxGa1-xAsyP1-y   1110  
  InP      
  InxGa1-xAsyP1-y   1110  
n-contact InP n = 1.5E18 Si doped    
SCL outer InGaAsP   1150+/-10  
SCL Inner InGaAsP 40   1250+/-10  
QW InGaAsP (x3) 1% compressive strain 1550+/‐ 10  
Barriers InGaAsP (x2) 0.3% tensile strain 1250+/‐10  
SCL Inner InGaAsP   1250+/-10 0.99  
SCL outer InGaAsP   1150+/-10  
  InP   Zn doped   p-doped from graded 1E18 near InGaAlAs to undoped near InGaAsP
TJ layer InGa(Al)As 10 p++ Zn-doped    
TJ layer InP    
  InP   n-doped from graded 1E18 near InP to undoped near InGaAsP
SCL outer InGaAsP   1150+/-10  
SCL Inner InGaAsP undoped   1250+/-10  
QW InGaAsP (x3) 7 per well 1550+/‐ 10  
Barriers InGaAsP (x2) 0.3% tensile strain 1250+/‐10  
SCL Inner InGaAsP   1250+/-10  
SCL outer InGaAsP   1150+/-10  
p-cladding InP Zn  doped   p-doped from graded 1E18 near InGaAs to undoped near QW
p-contact In.53Ga.47As Zn  doped    
Buffer InP Zn doped   1.34  
Substrate InP 350 um n-doped        

 

Note:

For the structure of InGaAsP / InP herterjuntions, tunnel junction (TJ) layer should use 1250nm AlGaInAs or InGaAsP, the reason is that the long wavelength has smaller resistivity but if too long wavelength, it would be absorption for emission wavelength. 80nm InGaAsP cannot stop TJ impurity lons spreading to QW, here we suggest increasing thickness. Maybe 240nm InGaAsP can stop the diffusion, we should test it.

No. 2 InGaAsP / InP LD Epitaxial Structure PAM200420-INGAASP

Layer Material Thickness Notes
Layer 7 InP
Layer 6 InGaAsP
Layer 5 InP
Layer 4 InGaAsP
Layer 3 InP
Layer 2 InGaAsP emitting at 1575 nm
Layer 1 InP
Substrate: InP, 3”

No. 3 InGaAsP Heteroepitaxial on InP for LD PAM200708-INGAASP

Epi Layer Material Thickness Energy Gap
Layer 7 InP 100nm  
Layer 6c InGaAsP @1.25 eV
Layer 6b InGaAsP @0.85 eV
Layer 6a InGaAsP @1.25 eV
Layer 5 InP  
Layer 4c InGaAsP 79 nm @1.25 eV
Layer 4b InGaAsP @0.95 eV
Layer 4a InGaAsP @1.25 eV
Layer 3 InP  
Layer 2c InGaAsP @1.25 eV
Layer 2b InGaAsP @0.85 eV
Layer 2a InGaAsP @1.25 eV
Layer 1 InP  
Substrate InP    

2. Growth of InGaAsP Layers

Compared with the ternary compound A1-xBxC, the band gap and lattice constant are determined by the same composition parameter x, while the quaternary compound A1-xBxCyD1-y can adjust the composition parameters x and y respectively to select different band gap and lattice constant. This adds variability and uncertainty to the epitaxial growth of the InGaAsP / InP double heterostructure (DH) wafer. For epitaxially grown quaternary materials, unless the device has special requirements, it is generally required to match the substrate lattice to avoid growth defects caused by lattice mismatch. For quaternary materials such as InxGa1-xAsyP1-y, because there are two composition ratios of III and V group elements, there can be countless combinations of x and y to meet the lattice matching requirements of the same substrate, which will bring great difficulties for adjustment and calibration of quaternary epitaxy parameters.

For the InGaAsP lattice matched to InP substrate, MBE technology is usually adopted. We can take advantage of the fact that the adhesion coefficient of group III elements is close to 100%, and the composition ratio between group III elements is relatively stable and repeatable. First, calibrate the composition distribution ratio of group III elements In and Ga, and then gradually adjust and calibrate the composition ratio between group V elements. Finally, the InGaAsP layers which are lattice matched with the InP substrate are obtained.

3. Chemical Etching of InGaAsP / InP Heterostructure

HBr:CH3COOH(H3PO4):K2Cr2O7 is a suitable solution for etching heteroepitaxial laser wafer grown with InGaAsP / InP MQW. This etching system can make the high quality etched surface without etch pits. For (001) InP, the etching rate changes from 0.1 to 10 um/min, which depends on the composition ration of solution or the normal line of K2Cr2O7 aqueous solution.

Mesa-like structures are formed on the (001) InP etched stripes parallel to the [110] and [110] directions. The etchant system etches InP and InGaAsP at nearly equal rates, thus providing ideal mesa-like structures with high-quality surfaces and good resist pattern definition. This solution does not corrode photoresist, making it attractive for kinds of device applications.

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