Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
183 words
A heterostructure bipolar transistor comprising an emitter layer (14, 24, 34), a base layer (13, 23, 33) and a collector layer (12, 22, 32), said emitter layer being formed of a semiconductor material whose energy gap is wider than that of said base layer, so that a heterojunction is formed between said emitter layer and said base layer, characterized in that one of said emitter layer and said base layer comprises first and second layers (14a, 14b, 23a, 23b) which are sequentially formed, said first layer (14a, 23a) constituting the heterojunction has a lower impurity concentration than that of said second layer (14b, 23b), and when the impurity concentration and the thickness of said first layer (14a, 23a) are defined as N 1 and W 1 , respectively, the following relation is satisfied: where q: absolute value of electron charge ( = 1 . 6 x 10 -19 Coulombs), ε 0 : free space permittivity ( = 8 .8 6 x 10 - 14 farads/cm), e sl : dielectric constant of said first layer, and V bi : built-in potential at said heterojunction.
Claim 2
Dependent Claim
183 words
A heterostructure bipolar transistor comprising an emitter layer (14, 24, 34), a base layer (13, 23, 33) and a collector layer (12, 22, 32), said emitter layer being formed of a semiconductor material whose energy gap is wider than that of said base layer, so that a heterojunction is formed between said emitter layer and said base layer, characterized in that one of said emitter layer and said base layer comprises first and second layers (14a, 14b, 23a, 23b) which are sequentially formed, said first layer (14a, 23a) constituting the heterojunction has a lower impurity concentration than that of said second layer (14b, 23b), and when the impurity concentration and the thickness of said first layer (14a, 23a) are defined as N 1 and W 1 , respectively, the following relation is satisfied: where q: absolute value of electron charge ( = 1 . 6 x 10 -19 Coulombs), ε 0 : free space permittivity ( = 8 .8 6 x 10 - 14 farads/cm), e sl : dielectric constant of said first layer, and V bi : built-in potential at said heterojunction.
Claim 3
Dependent Claim
144 words
A transistor according to claim 1, characterized in that the other of said emitter layer (34) and said base layer (33) comprise a third layer (33b, 34a) and a fourth layer (33a, 34b) which are sequentially formed, the impurity concentration of said third layer (33b, 34a) constituting the heterojunction is lower than that of said fourth layer (33a, 34b), and the following relation is satisfied when the impurity concentration and the thickness of said third layer are defined as N 2 and W 2 , respectively: where q: absolute value of electron charge ( = 1 . 6 x 10 -19 C oulombs), ε 0 : free space permittivity ( = 8.8 6 x 10 -14 farads/cm), ε s1 : dielectric constant of said first layer, ε s2 : dielectric constant of said second layer, and V bi : built-in potential at the heterojunction.
Claim 4
Dependent Claim
40 words
A transistor according to claim 1 or 2, characterized in that said emitter layer (14, 24, 34) is formed of Ga 1-x Aℓ x As, said base layer (13, 23, 33) GaAs, and said collector layer (12, 22, 32) GaAs.
Claim 5
Dependent Claim
40 words
A transistor according to claim 1 or 2, characterized in that said emitter layer (14, 24, 34) is formed of Ga 1-x Aℓ x As, said base layer (13, 23, 33) GaAs, and said collector layer (12, 22, 32) GaAℓAs.