In seeking for semiconductor lasers with simple fabrication process and good performance

plenty of lager structures has been developed to realize the current confinement in lateral direction.As an effective way for this purpose

it was considered to form a current blocking layer inside the heterostructure and then allow the current to flow within a narrow path

as in the case of VSIS laser.In VSIS laser

two-Step epitaxial growth and photolithography and V-groovc etching on the epitaxial wafer are inevitable.Recently

we designed a laser with new structure

the terraced substrate inner stripe laser(TSIS).The TSIS laser has a simple fabrication process.It is fabricated by one-step liquid phase epitaxy without mask deposition and Zn diffusion.However

this TSIS laser needs a precise control of melt saturation and growth time of the current confinement layer.To make the laser fabrication process even simpler

a new structure laser with a narrow mesa substrate is developed(Fig.1).This new narrow mesa substrate inner stripe laser(NMSIS)is fabricated by simillar techniques to TSIS laser

using one-step liquid phase epitaxy without mask deposition and Zn diffusion.After a narrow trapezoidal mesa is etched on the substrate

making use of the properties of liquid phase epitaxy over a non-planar substrate

the growth of all layers including GaAlAs current confinement layer is accomplished by one-step liquid phase epitaxy.In growing the current confinement layer(first one)

because the growth melt is effectively undersatu-rated for convex areas and the lateral diffusion is induced by local Solute concentration gradient between convex areas and concave ones

the shoulder of the mesa is melt-etched

the region on the mesa is just saturated

and at the same time the epitaxy layer is formed on the areas beyond the mesa part.By using this technique of crystal growth

the inner stripe for current channel is as narrow as 3 to 5um on the meSa.The confinement layer could be contiolled as thick as desirable.It's over 1μm in our experiment

which is enough to prevent the current leakage outside current channel.Apart from the very simple fabrication process of this structure

there are some other advantages.The spontaneous absorption in confinement layer instead of GaAs is reduced.Primarily

the lasers stimulate with threshold current of 80~120mA and the wavelength of 7800-8100Å.Since the NMSIS laser is narrow gain guide

the laser has linear power veisus current characteristics and fundamental mode operation with up to 3-4 times threshold current and over 25mW maxium power output.The relation of field distribution to the current path width has been studied.The far field patterns in single

double and triple peaks in fundamental lateral mode are found in different cunent channel width.