Optical device with low electrical and thermal resistance bragg reflectors

Claim 2

An optical device comprising at least one distributed Bragg reflector mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair having an index of refraction which is different from the index of refraction of the other layer in each pair, any two adjacent semiconductor layers of the distributed Bragg reflector mirror forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer is composition graded from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer is composition graded from the third composition to the second composition, the second region having a smaller variation in composition with distance in the growth direction than the first region.

Claim 3

The optical device of claim 1 in which a thickness in the growth direction of the first region of each heterojunction is smaller than the thickness of the second region of each heterojunction.

Claim 4

The optical device of claim 1 in which an absolute magnitude of a second derivative of a bandgap energy with distance in the growth direction is smaller in the second region than in the first region.

Claim 5

The optical device of claim 1 in which the second region of each heterojunction is at least in part semiparabolically graded in composition.

Claim 6

The optical device of claim 1 in which the first and second regions of each heterojunction are at least in part semiparabolically graded in composition.

Claim 7

The optical device of claim 1 in which the second region is modulation doped.

Claim 8

The optical device of claim 1 in which the distributed Bragg reflector mirror is a unipolar, p-type structure.

Claim 9

The optical device of claim 1 in which the device is a light-emitting device selected from the group consisting of a vertical-cavity surface-emitting laser, a light-emitting diode, and a resonant-cavity light-emitting diode.

Claim 10

The optical device in claim 1 in which the device is a resonant-cavity photodetector.

Claim 11

An optical device comprising at least one distributed Bragg reflector mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair having an index of refraction which is different from the index of refraction of the other layer in each pair, any two adjacent semiconductor layers of the distributed Bragg reflector mirror forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer is abruptly varied in composition from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer is smoothly varied in composition from the third composition to the second composition.

Claim 12

An optical device comprising at least one distributed Bragg reflector mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair having an index of refraction which is different from the index of refraction of the other layer in each pair, any two adjacent semiconductor layers of the distributed Bragg reflector mirror forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer is abruptly varied in composition from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer is smoothly varied in composition from the third composition to the second composition.

Claim 13

The optical device of claim 10 in which a thickness in the growth direction of the first region of each heterojunction is smaller than the thickness of the second region of each heterojunction.

Claim 14

The optical device of claim 10 in which an absolute magnitude of a second derivative of a bandgap energy with distance in the growth direction is smaller in the second region than in the first region.

Claim 15

The optical device of claim 10 in which the second region of each heterojunction is at least in part semiparabolically graded in composition.

Claim 16

The optical device of claim 10 in which the first and second regions of each heterojunction are at least in part semiparabolically graded in composition.

Claim 17

The optical device of claim 10 in which the second region is modulation doped.

Claim 18

The optical device of claim 10 in which the distributed Bragg reflector mirror is a unipolar, p-type structure.

Claim 19

The optical device of claim 10 in which the device is a light-emitting device selected from the group consisting of a vertical-cavity surface-emitting laser, a light-emitting diode, and a resonant-cavity light-emitting diode.

Claim 20

The optical device in claim 10 in which the device is a resonant-cavity photodetector.

Claim 21

An optical device comprising: (a) n-type and p-type semiconductor distributed Bragg reflector mirrors, each mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair of semiconductor layers having an index of refraction which is different from the index of refraction of the other layer in each pair of semiconductor layers, any two adjacent semiconductor layers of the distributed Bragg reflector mirror forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer is composition graded from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer is composition graded from the third composition to the second composition, the second region having a smaller variation in composition with distance in the growth direction than the first region; (b) an active region formed between the n-type and p-type mirrors; and (c) electrodes operatively connected to the n-type and p-type mirrors for applying a bias voltage therebetween.

Claim 22

An optical device comprising: (a) n-type and p-type semiconductor distributed Bragg reflector mirrors, each mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair of semiconductor layers having an index of refraction which is different from the index of refraction of the other layer in each pair of semiconductor layers, any two adjacent semiconductor layers of the distributed Bragg reflector mirror forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer is composition graded from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer is composition graded from the third composition to the second composition, the second region having a smaller variation in composition with distance in the growth direction than the first region; (b) an active region formed between the n-type and p-type mirrors; and (c) electrodes operatively connected to the n-type and p-type mirrors for applying a bias voltage therebetween.

Claim 23

The optical device of claim 19 in which a thickness in the growth direction of the first region of each heterojunction is smaller than the thickness of the second region of each heterojunction.

Claim 24

The optical device of claim 19 in which an absolute magnitude of a second derivative of a bandgap energy with distance in the growth direction is smaller in the second region than in the first region.

Claim 25

The optical device of claim 19 in which the second region of each heterojunction is at least in part semiparabolically graded in composition.

Claim 26

The optical device of claim 19 in which the first and second regions of each heterojunction are at least in part semiparabolically graded in composition.

Claim 27

The optical device of claim 19 in which the second region is modulation doped.

Claim 28

The optical device of claim 19 in which the device is a light-emitting device selected from the group consisting of a vertical-cavity surface-emitting laser, a light-emitting diode, and a resonant-cavity light-emitting diode.

Claim 29

The optical device of claim 19 in which the device is a resonant-cavity photodetector.

Claim 30

The optical device of claim 19 further including a plurality of pairs of dielectric layers formed above the last-grown distributed Bragg reflector mirror for increasing a reflectivity thereof, the index of refraction of one dielectric layer in each pair of dielectric layers being different from the other dielectric layer in each pair of dielectric layers.

Claim 31

An optical device comprising: (a) n-type and p-type semiconductor distributed Bragg reflector mirrors, each mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair having an index of refraction which is different from the index of refraction of the other layer of the pair, any two adjacent semiconductor layers forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer of at least one of the distributed Bragg reflector mirrors is abruptly varied in composition from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer of the same at least one distributed Bragg reflector mirror is smoothly varied in composition from the third composition to the second composition; (b) an active region formed between the n-type and p-type mirrors; and (c) electrodes operatively connected to the n-type and p-type mirrors for applying a bias voltage therebetween.

Claim 32

An optical device comprising: (a) n-type and p-type semiconductor distributed Bragg reflector mirrors, each mirror having at least one pair of semiconductor layers epitaxially grown one upon another, one layer in each pair having an index of refraction which is different from the index of refraction of the other layer of the pair, any two adjacent semiconductor layers forming a heterojunction, a first layer of the two adjacent layers having a first composition and a first bandgap and a second layer of the two adjacent layers having a second composition and a second bandgap, the second bandgap being greater than the first bandgap, characterized in that a first region of each heterojunction adjacent to the first layer of at least one of the distributed Bragg reflector mirrors is abruptly varied in composition from the first composition to a third composition intermediate between the first and second compositions, and a second region of each heterojunction adjacent to the second layer of the same at least one distributed Bragg reflector mirror is smoothly varied in composition from the third composition to the second composition; (b) an active region formed between the n-type and p-type mirrors; and (c) electrodes operatively connected to the n-type and p-type mirrors for applying a bias voltage therebetween.

Claim 33

The optical device of claim 28 in which the second region of each heterojunction is semiparabolically graded in composition.

Claim 34

The optical device of claim 28 in which the second region is modulation doped.

Claim 35

The optical device of claim 28 in which the device is a light-emitting device selected from the group consisting of a vertical-cavity surface-emitting laser, a light-emitting diode, and a resonant-cavity light-emitting diode.

Claim 36

The optical device of claim 28 further including a plurality of pairs of dielectric layers formed above one of the distributed Bragg reflector mirrors for increasing a reflectivity thereof, the index of refraction of one dielectric layer in each pair of dielectric layers being different from the other dielectric layer in each pair of dielectric layers.

Claim 37

The optical device of claim 28 in which the device is a light-emitting device selected from the group consisting of a vertical-cavity surface-emitting laser, a light-emitting diode, and a resonant-cavity light-emitting diode.

Claim 38

The optical device of claim 28 in which the device is a resonant-cavity photodetector.