Light-emitting semiconductor device using group III nitrogen compound

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The invention-will be more fully understood by reference to the following examples.
EXAMPLE 1 FIG.
1 shows a LED 10 embodied in Example 1.
It has a sapphire (Al.
sub.
2O.
sub.
3) substrate 1 upon which the following five layers are consecutively formed: an AlN buffer layer 2; a silicon (Si) doped GaN n.
sup.
+-layer 3 of high carrier (n-type) concentration; a Si-doped (Al.
sub.
x2Ga.
sub.
1-x2).
sub.
y2In.
sub.
1-y2N n.
sup.
+-layer 4 of high carrier (n-type) concentration; a cadmium (Cd) and Si-doped (Al.
sub.
x1Ga.
sub.
1-x1).
sub.
y1In.
sub.
1-y1N emission layer 5; and a Mg-doped (Al.
sub.
x2Ga.
sub.
1-x2).
sub.
y2In.
sub.
1-y2N p-layer 6.
The AlN layer 2 has 500 .
ANG.
thickness.
The GaN n.
sup.
+-layer 3 is about 2.
0 .
mu.
m in thickness and has a 2.
times.
10.
sup.
18/cm.
sup.
3 electron concentration.
The n.
sup.
+-layer 4 is about 2.
0 .
mu.
m in thickness and has a 2.
times.
10.
sup.
18/cm.
sup.
3 electron concentration.
The emission layer 5 is about 0.
5 .
mu.
m in thickness.
The i-layer 6 is about 1.
0 .
mu.
m in thickness and has a 2.
times.
10.
sup.
17/cm.
sup.
3 hole concentration.
Nickel electrodes 7 and 8 are connected to the p-layer 6 and the n.
sup.
+-layer 4, respectively.
They are electrically insulated by a groove 9.
The LED 10 is produced by gaseous phase growth, called metal organic vapor phase epitaxy referred to as MOVPE hereinafter.
The gases employed in this process are ammonia (NH.
sub.
3), a carrier gas (H.
sub.
2 or N.
sub.
2), trimethyl gallium (Ga(CH.
sub.
3).
sub.
3) (TMG hereinafter), trimethyl aluminum (Al(CH.
sub.
3).
sub.
3) (TMA hereinafter), trimethyl indium (In(CH.
sub.
3).
sub.
3) (TMI hereinafter), dimethylcadmium ((Cd(CH.
sub.
3).
sub.
2) (DMCd hereinafter), silane (SiH.
sub.
4), diethylzinc ((C.
sub.
2H.
sub.
5).
sub.
2Zn) (DEZ hereinafter) and biscyclopentadienyl magnesium (Mg(C.
sub.
5H.
sub.
5).
sub.
2) (CP.
sub.
2Mg hereinafter).
The single crystalline sapphire substrate 1, whose main surface `a` was cleaned by an organic washing solvent and heat treatment, was placed on a susceptor in a reaction chamber for the MOVPE treatment