Info
Info
News Article

Researchers Grow High-performance InAs/GaAs Quantum Dot Laser On Silicon

Lasing operation up to 111degC with output power over 100mW at room temperature

Researchers from University College London (UCL) in the UK, and University of Arkansas in the US have grown a high-performance InAs/GaAs quantum dot laser directly on a silicon substrate. Their work was published last month in the journal Electronics Letters.

Growing III-V semiconductors on silicon substrates is tricky due to the formation of high-density threading dislocations. These dislocations, resulting from the lattice mismatch and thermal expansion coefficient between III-V compounds and silicon, propagate into the active media and degrade the laser performance. Therefore, for direct growth of III-V on silicon substrates, dislocation filter layers between silicon and III-V active element play a crucial role.

A few years ago, the UCL team was first to show the operation of an electrically pumped InAs/GaAs quantum-dot laser epitaxially grown on a silicon substrate. This was achieved using InGaAs/GaAs strained layer superlattices as dislocation filter layers to reduce the density of the threading dislocations. The team has since been optimising this buffer layer and this latest work shows that a higher performance can be achieved using InAlAs/GaAs.

The InAs/GaAs QD laser structure was grown on silicon substrates by molecular beam epitaxy. The schematic layer structure is shown above.

The epitaxy layer starts with a 1µm-thick n-type GaAs buffer layer, followed by InAlAs/GaAs DFLs, above this is a 1.5µm-thick n-type AlGaAs lower cladding layer and a 30nm-thick undoped AlGaAs guiding layer, followed by the undoped active region. Above the active region, a second 30nm-thick undoped AlGaAs guiding layer, a 1.5µm-thick p-type AlGaAs up cladding layer, and finally a 300nm-thick highly p-doped GaAs contact layer were deposited.

The active region consists of five-layer InAs/InGaAs dot-in-a-well (DWELL) structure,consisting of three monolayers of InAs grown on 2nm of In0.15Ga0.85As and capped by 6nm of In0.15Ga0.85As. The InAs/InGaAs DWELLs were separated by 45nm GaAs spacer layer. The InAs/InGaAs DWELLs were separated by 45nm GaAs spacer layer. For the growth of InAlAs/GaAs DFLs, first three repeats of five-periods of a 10nm In0.15Al0.85As/10nm GaAs superlattice were grown, with each layers of DFLs were each separated by a 400nm GaAs barrier, followed by a 50 periods of GaAs (5nm)/AlGaAs (5nm) superlattice, above this is grown another two repeats of five-periods of a 10nm In0.15Al0.85As/10nm GaAs superlattice.

By taking this approach, the researchers demonstrated the highest lasing temperature for InAs/GaAs QDs lasers directly grown on silicon substrates. (A laser designed for silicon photonics needs to work at a high temperature as modern silicon electronic chips often work at 65degC). The team reported that the device exhibits lasing at 1.26µm with a threshold current density of 200A/cm2 along with single facet output power exceeding 100mW at room temperature. Significantly, lasing operation for heatsink temperature up to 111degC has been achieved.

'1.3µm InAs/GaAs quantum-dot laser monolithically grown on Si substrates operating over 100degC' by SM Chen et al appeared in Electronics Letters, Volume 50, Issue 20, 25 September 2014.  DOI: 10.1049/el.2014.2414



AngelTech Live III: Join us on 12 April 2021!

AngelTech Live III will be broadcast on 12 April 2021, 10am BST, rebroadcast on 14 April (10am CTT) and 16 April (10am PST) and will feature online versions of the market-leading physical events: CS International and PIC International PLUS a brand new Silicon Semiconductor International Track!

Thanks to the great diversity of the semiconductor industry, we are always chasing new markets and developing a range of exciting technologies.

2021 is no different. Over the last few months interest in deep-UV LEDs has rocketed, due to its capability to disinfect and sanitise areas and combat Covid-19. We shall consider a roadmap for this device, along with technologies for boosting its output.

We shall also look at microLEDs, a display with many wonderful attributes, identifying processes for handling the mass transfer of tiny emitters that hold the key to commercialisation of this technology.

We shall also discuss electrification of transportation, underpinned by wide bandgap power electronics and supported by blue lasers that are ideal for processing copper.

Additional areas we will cover include the development of GaN ICs, to improve the reach of power electronics; the great strides that have been made with gallium oxide; and a look at new materials, such as cubic GaN and AlScN.

Having attracted 1500 delegates over the last 2 online summits, the 3rd event promises to be even bigger and better – with 3 interactive sessions over 1 day and will once again prove to be a key event across the semiconductor and photonic integrated circuits calendar.

So make sure you sign up today and discover the latest cutting edge developments across the compound semiconductor and integrated photonics value chain.

REGISTER FOR FREE

VIEW SESSIONS

Info
×
Search the news archive

To close this popup you can press escape or click the close icon.
×
Logo
×
Register - Step 1

You may choose to subscribe to the Compound Semiconductor Magazine, the Compound Semiconductor Newsletter, or both. You may also request additional information if required, before submitting your application.


Please subscribe me to:

 

You chose the industry type of "Other"

Please enter the industry that you work in:
Please enter the industry that you work in:
 
X
Info
X
Info
{taasPodcastNotification}
Live Event